A core-shell structured TiO2 / C2N composite material, its preparation method and application
By preparing a core-shell structured TiO2/C2N composite material, the problem of selectively removing trace amounts of new pollutants in complex water bodies was solved by utilizing the C2N shell to exclude large-molecule natural organic matter. This achieved the effect of efficient and selective degradation of new pollutants.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUN YAT SEN UNIV
- Filing Date
- 2024-04-03
- Publication Date
- 2026-08-04
AI Technical Summary
Existing TiO2 photocatalytic materials have difficulty selectively removing trace amounts of new pollutants in complex water bodies, especially due to interference from natural organic matter, which leads to a decrease in catalytic activity.
A core-shell structured TiO2/C2N composite material was prepared by chemical vapor deposition. By forming a C2N shell on the surface of TiO2, the nanoscale pore size of the C2N shell excludes large molecular natural organic matter, allowing only small molecule new pollutants to enter the active sites of TiO2 for degradation.
It achieves highly efficient and selective removal of new pollutants in complex water bodies, with degradation rates unaffected by natural organic matter. It is simple to operate, environmentally friendly, and suitable for actual production.
Smart Images
Figure CN118437366B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pollutant treatment technology. More specifically, it relates to a core-shell structured TiO2 / C2N composite material, its preparation method, and its applications. Background Technology
[0002] The production and use of toxic and hazardous chemicals are major sources of emerging pollutants. Currently, emerging pollutants of widespread concern both domestically and internationally mainly include persistent organic pollutants (POPs), endocrine disruptors, and antibiotics, all regulated by international conventions. In recent years, with the rapid development of industry, various emerging pollutants have flooded into aquatic ecosystems, posing a serious threat to humans and aquatic plants and animals worldwide. These pollutants not only negatively impact water quality but also disrupt ecological balance, exacerbating the threat to sustainable development. Photocatalysis refers to the process where semiconductor materials are excited under ultraviolet or visible light irradiation, causing electrons to transition from the valence band to the conduction band, forming photogenerated electron-hole pairs. This converts light energy into chemical energy, producing more reactive species with stronger oxidizing properties, thereby promoting the degradation of organic matter. Due to its advantages such as mild reaction conditions, environmental friendliness, no treatment byproducts, and no secondary pollution, it is considered the most promising green and environmentally friendly technology and is widely used in the field of organic matter degradation technology.
[0003] Titanium dioxide (TiO2) is a widely studied photocatalytic material with many advantages: chemical stability, wide availability and low cost, no photocorrosion, strong acid and alkali resistance, strong redox properties, and non-toxicity to organisms. However, TiO2 currently faces many problems in practical applications: it is difficult to separate from the reaction system after reaction, it is easily lost, it has poor recyclability, it can cause secondary pollution, and its catalytic activity is limited. To overcome these shortcomings, existing technologies often modify TiO2 into heterogeneous titanium dioxide structures (metal / TiO2, metal oxide / TiO2, metal sulfide / TiO2, metal-free compound / TiO2) to improve its catalytic activity. For example, Han Zhiguo et al. optimized the performance of titanium dioxide by coupling it with other semiconductors, element doping, and precise control of its morphology to prepare AgI@TiO2@UiO-66, and found that its photocatalytic activity for norfloxacin was significantly enhanced compared with titanium dioxide alone (Han Zhiguo, Zhao Suya, Zhu Yu. Preparation of AgI@TiO2@UiO-66 composite material and study on photodegradation of norfloxacin [J]. Anhui Chemical Industry, 2023, 49(05):79-83.).
[0004] However, in actual water bodies, the concentration of natural organic matter (NOM) is much higher than that of new pollutants (three times or more), typically reaching mg / L. This means that when catalysts are applied to water, the active sites on the catalyst are preferentially occupied by high concentrations of NOM, inhibiting the adsorption and degradation of new pollutants. Simultaneously, NOM can react with reactive oxides, leading to the significant consumption of reactive oxides used for the degradation of new pollutants, greatly reducing the removal efficiency. Therefore, there is an urgent need to develop novel photocatalytic systems to efficiently and selectively remove trace amounts of new pollutants from complex water bodies. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing technology in selectively removing trace new pollutants in complex water bodies, and to provide a core-shell structured TiO2 / C2N composite material.
[0006] The purpose of this invention is to provide a method for preparing a core-shell structured TiO2 / C2N composite material.
[0007] Another objective of this invention is to provide an application of a core-shell structured TiO2 / C2N composite material.
[0008] The above-mentioned objective of this invention is achieved through the following technical solution:
[0009] A method for preparing a core-shell structured TiO2 / C2N composite material, specifically including the following steps:
[0010] 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN) was dissolved in ethanol, and TiO2 powder was added. The mixture was sonicated for 0.5–1.5 h, stirred, and dried to obtain a precursor mixture TiO2 / HAT-CN. TiO2 / HAT-CN was calcined at 500–600 °C for 1–3 h in an inert gas atmosphere, then naturally cooled, and post-treated to obtain a core-shell structured TiO2 / C2N composite material.
[0011] This invention utilizes chemical vapor deposition to obtain a core-shell structure. First, a nitrogen source and titanium dioxide are thoroughly mixed and dried. In the resulting TiO2 / HAT-CN precursor, due to the thorough mixing of HAT-CN and TiO2, the space between TiO2 particles is expanded by HAT-CN, which is beneficial for exposing the surface sites of TiO2. This greatly reduces the particle stacking of TiO2 nanoparticles and fully exposes the surface sites, facilitating subsequent C2N deposition. High-temperature calcination causes the nitrogen source to form gaseous C2N at high temperature, which naturally deposits on TiO2 during the cooling process to form a shell, thus obtaining the core-shell structured TiO2 / C2N composite material of this invention.
[0012] Furthermore, the ultrasound duration is 1 to 1.5 hours; preferably, the ultrasound duration is 1 hour.
[0013] Furthermore, the specific conditions for calcination are as follows: heating from room temperature to 70-90°C at a heating rate of 1-3°C / min, holding at that temperature for 0.5-1.5 hours; then heating from 70-90°C to 500-600°C at a heating rate of 4°C / min, holding at that temperature for 1-3 hours.
[0014] Preferably, the specific conditions for calcination are as follows: heating from room temperature to 80°C at a heating rate of 2°C / min and holding at that temperature for 1 hour; then heating from 80°C to 500-600°C at a heating rate of 4°C / min and holding at that temperature for 2 hours.
[0015] More preferably, the specific conditions for calcination are as follows: heating from room temperature to 80°C at a heating rate of 2°C / min and holding at that temperature for 1 hour; then heating from 80°C to 550°C at a heating rate of 4°C / min and holding at that temperature for 2 hours.
[0016] Furthermore, the stirring time is 6 to 18 hours; preferably, the stirring time is 12 hours.
[0017] Further, the concentration of HAT-CN in the ethanol is 5-15 g / L; preferably, the concentration of HAT-CN in the ethanol is 10 g / L.
[0018] Preferably, the HAT-CN is dissolved in ethanol by ultrasonic mixing, wherein the ultrasonic mixing time is 0.5 to 1.5 hours; more preferably, the ultrasonic mixing time is 1 hour.
[0019] Further, the mass ratio of HAT-CN to TiO2 is 1:10 to 100; preferably, the mass ratio of HAT-CN to TiO2 is 1:50.
[0020] Meanwhile, the present invention also protects the core-shell structure TiO2 / C2N composite material; wherein, the C2N is a shell wrapped around the core structure TiO2.
[0021] In the core-shell structured TiO2 / C2N composite material prepared by this invention, TiO2 / C2N form a type II heterojunction with reaction sites on the surface of the core TiO2. Therefore, small molecule pollutants can pass through C2N to enter the TiO2 surface and be degraded, while large molecule natural organic matter is excluded from the reaction sites by C2N, thereby reducing the interference of natural organic matter on the degradation reaction of trace new pollutants.
[0022] In addition, the present invention also protects the application of the core-shell structured TiO2 / C2N composite material in the photocatalytic degradation of new pollutants in water.
[0023] Furthermore, the new pollutants are persistent organic pollutants, endocrine disruptors, and antibiotics.
[0024] Persistent organic pollutants (POPs) are synthetic chemicals that persist in the environment, accumulate through the food chain, and have harmful effects on human health. They possess four characteristics: high toxicity, persistence, bioaccumulation, and long-distance migration. For humans, who are at the top of the food chain, these toxicities are amplified more than 70,000 times compared to their initial state.
[0025] Preferably, the persistent organic pollutants include, but are not limited to, carbamazepine, ibuprofen, and metronidazole.
[0026] A method for selectively degrading new pollutants in water using an ultraviolet / TiO2 / C2N system involves adding the core-shell structured TiO2 / C2N composite material described in this invention to the water to be treated, stirring until homogeneous, and simultaneously turning on an ultraviolet lamp to begin the degradation of the new pollutants.
[0027] Specifically, in the embodiments of this application, carbamazepine was selected as a new model pollutant. NOM was added to the carbamazepine solution, and then the core-shell structured TiO2 / C2N composite material was added and stirred evenly. At the same time, the ultraviolet lamp was turned on to start the degradation experiment.
[0028] Furthermore, the concentration of carbamazepine is 1–10 μM, preferably 5 μM.
[0029] Furthermore, the concentration of NOM is 1–5 mg / L, preferably 2 mg / L.
[0030] Furthermore, the dosage of TiO2 / C2N is 1 to 100 mg / L, preferably 10 mg / L.
[0031] Furthermore, the wavelength of the ultraviolet light is 254–365 nm, preferably 365 nm.
[0032] Degradation reaction principle: The nanoscale pores of the C2N shell exclude large NOM molecules from the active sites of TiO2, while allowing small new pollutants to pass through the C2N shell into the active sites of TiO2. Under ultraviolet light excitation, TiO2 can generate oxidizing species to rapidly degrade the new pollutants on the active sites without being disturbed by NOM, thus greatly improving the degradation rate.
[0033] The present invention has the following beneficial effects:
[0034] This invention utilizes chemical vapor deposition (CVD) followed by calcination and natural cooling to obtain a core-shell structured TiO2 / C2N composite material. The core-shell structure of this invention selectively degrades trace amounts of new pollutants in real water bodies. The nanoscale pores of the C2N shell exclude large-molecule natural organic matter (NOM) from the active sites of TiO2, while allowing small-molecule new pollutants to permeate through the C2N shell and distribute evenly within the active sites of TiO2. Under ultraviolet light excitation, TiO2 generates oxidizing species that rapidly degrade new pollutants at the active sites without interference from NOM. This invention significantly suppresses the influence of NOM in real water bodies on the photocatalytic degradation of new pollutants, achieving highly efficient and selective removal of new pollutants in complex water quality environments. The preparation method of this composite material is simple, environmentally friendly, pollution-free, and highly efficient, making it suitable for practical production. Furthermore, the photocatalytic degradation system of this invention is simple to operate, consumes little energy, has low cost, short reaction time, and exhibits significant new pollutant removal effects, making it of great significance for the degradation of new pollutants in practical production and daily life. Attached Figure Description
[0035] Figure 1 This is a schematic diagram of the synthesis method of a core-shell structured TiO2 / C2N composite material according to the present invention.
[0036] Figure 2 The images show transmission electron microscope (a) and elemental mapping (b) images of the core-shell structured TiO2 / C2N composite material prepared in Example 1, as well as X-ray photoelectron spectroscopy (c) and pore size distribution (d) of the C2N shell.
[0037] Figure 3 These are transmission electron microscope (TEM) images of TiO2 / C2N prepared in Example 2 (a); TEM images of TiO2 / C2N prepared in Example 3 (b); TEM images of TiO2 / C2N prepared in Comparative Example 2 (c); and TEM images of TiO2 / C2N prepared in Comparative Example 3 (d).
[0038] Figure 4 This is a graph showing the first-order rate constants of the degradation of carbamazepine by the core-shell structure TiO2 / C2N prepared in Example 1 and the TiO2 / C2N prepared in Comparative Example 1 under ultraviolet light irradiation in water with NOM concentrations of 0, 1, 2, and 5 mg / L.
[0039] Figure 5The images shown are: transmission electron microscope (a) and elemental mapping (b) images of the core-shell TiO2 / C3N4 composite material of the control group in this embodiment of the invention; X-ray photoelectron spectroscopy (C) of the C3N4 shell; and first-order rate constants (d) of the degradation of carbamazepine by TiO2 / C2N and TiO2 / C3N4 in water with NOM concentrations of 0, 1, 2, and 5 mg / L under ultraviolet light irradiation. Detailed Implementation
[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.
[0041] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.
[0042] Example 1
[0043] The experimental steps for synthesizing a core-shell structured TiO2 / C2N composite material in this embodiment are as follows:
[0044] First, 100 mg of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene (HAT-CN) was dispersed in 10 mL of ethanol and sonicated for 1 hour to completely dissolve HAT-CN. Then, 5 g of TiO2 powder was dispersed in the above solution, sonicated for 1 hour, and magnetically stirred for 12 hours. Next, the mixture was placed in a drying oven to remove the ethanol, yielding the precursor mixture TiO2 / HAT-CN. TiO2 / HAT-CN was placed in a tube furnace purged with argon gas and heated from room temperature to 80°C at a rate of 2°C / min, holding at this temperature for 1 hour; subsequently, the temperature was increased from 80°C to 550°C at a rate of 4°C / min, holding at this temperature for 2 hours. After natural cooling, the sample was washed three times with deionized water and anhydrous ethanol, respectively, to remove unreacted chemicals. The sample was then dried in a drying oven to obtain a core-shell structured TiO2 / C2N composite material.
[0045] A schematic diagram of the synthesis method of a core-shell structured TiO2 / C2N composite material of the present invention is shown below. Figure 1 As shown, this invention first thoroughly mixes HAT-CN and TiO2 in ethanol to obtain a TiO2 / HAT-CN precursor. Then, through high-temperature calcination, the nitrogen source forms gaseous C2N at high temperature. During cooling, C2N naturally deposits on TiO2 to form a shell, thus obtaining the core-shell structured TiO2 / C2N composite material of this invention. Transmission electron microscopy images of the composite material are shown below. Figure 2 As shown in (a), the C2N shell's coating of TiO2 is clearly visible; the elemental mapping image of the composite material is shown in [image missing]. Figure 2As shown in (b), the successful synthesis of the core-shell structured TiO2 / C2N composite material is further demonstrated; the X-ray photoelectron spectrum of the C2N shell is as follows. Figure 2 As shown in (c), the CN ratio is 2.1:1, indicating the successful synthesis of the C2N shell; the pore size distribution of the C2N shell is as follows. Figure 2 As shown in (d), the pore size of the C2N shell is approximately 2.9 nm, which is smaller than the average size of common NOM (>1 μm) and larger than the size of common new pollutants (<1.5 nm). Therefore, it is beneficial to exclude NOM from TiO2 active sites and allow new pollutants to enter TiO2 active sites, thereby achieving selective degradation of new pollutants in complex water bodies.
[0046] Example 2
[0047] The experimental steps for synthesizing a core-shell structured TiO2 / C2N composite material in this embodiment are as follows:
[0048] First, 100 mg of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene (HAT-CN) was dispersed in 10 mL of ethanol and sonicated for 1 hour to completely dissolve HAT-CN. Then, 5 g of TiO2 powder was dispersed in the above solution, sonicated for 1 hour, and magnetically stirred for 12 hours. Next, the mixture was placed in a drying oven to remove the ethanol, yielding the precursor mixture TiO2 / HAT-CN. TiO2 / HAT-CN was placed in a tube furnace purged with argon gas and heated from room temperature to 80°C at a rate of 2°C / min, holding at this temperature for 1 hour; subsequently, the temperature was increased from 80°C to 600°C at a rate of 4°C / min, holding at this temperature for 2 hours. After natural cooling, the sample was washed three times with deionized water and anhydrous ethanol, respectively, to remove unreacted chemicals. The sample was then dried in a drying oven to obtain the core-shell structured TiO2 / C2N composite material.
[0049] The difference between this and the core-shell structure TiO2 / C2N composite material in Example 1 is that the calcination temperature of 550℃ is replaced with 600℃.
[0050] Transmission electron microscope images of composite materials, as shown Figure 3 As shown in (a), the C2N shell can be clearly seen coating the TiO2.
[0051] Example 3
[0052] The experimental steps for synthesizing a core-shell structured TiO2 / C2N composite material in this embodiment are as follows:
[0053] First, 100 mg of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene (HAT-CN) was dispersed in 10 mL of ethanol and sonicated for 1 hour to completely dissolve HAT-CN. Then, 5 g of TiO2 powder was dispersed in the above solution, sonicated for 1.5 hours, and magnetically stirred for 12 hours. Next, the mixture was placed in a drying oven to remove the ethanol, yielding the precursor mixture TiO2 / HAT-CN. TiO2 / HAT-CN was placed in a tube furnace purged with argon gas and heated from room temperature to 80°C at a rate of 2°C / min, holding at this temperature for 1 hour; subsequently, the temperature was increased from 80°C to 550°C at a rate of 4°C / min, holding at this temperature for 2 hours. After natural cooling, the sample was washed three times with deionized water and anhydrous ethanol, respectively, to remove unreacted chemicals. The sample was then dried in a drying oven to obtain the core-shell structured TiO2 / C2N composite material.
[0054] Compared with the core-shell structure TiO2 / C2N composite material in Example 1, the difference is that the ultrasonication for 1 hour is replaced with ultrasonication for 1.5 hours.
[0055] Transmission electron microscope images of composite materials, as shown Figure 3 As shown in (b), the C2N shell can be clearly seen coating the TiO2.
[0056] Comparative Example 1: Preparation of physically mixed TiO2 / C2N
[0057] First, 100 mg of HAT-CN was placed in a tube furnace purged with argon gas and heated from room temperature to 80°C at a rate of 2°C / min, and held at that temperature for 1 hour. Then, the temperature was increased from 80°C to 550°C at a rate of 4°C / min, and held for 2 hours. After natural cooling, the sample was washed three times with deionized water and anhydrous ethanol, respectively, to remove unreacted chemicals. After drying, C2N was obtained. 0.1 g of C2N and 5 g of TiO2 were ultrasonicated in deionized water for 1 hour, stirred for 6 hours, and dried to obtain a physically mixed TiO2 / C2N.
[0058] Comparative Example 2: TiO2 / C2N prepared by changing the ultrasonic time
[0059] First, 100 mg of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene (HAT-CN) was dispersed in 10 mL of ethanol and sonicated for 1 hour to completely dissolve HAT-CN. Then, 5 g of TiO2 powder was dispersed in the above solution, sonicated for 10 minutes, and magnetically stirred for 12 hours. Next, the mixture was placed in a drying oven to remove the ethanol, yielding the precursor mixture TiO2 / HAT-CN. TiO2 / HAT-CN was placed in a tube furnace purged with argon gas and heated from room temperature to 80°C at a rate of 2°C / min, holding at this temperature for 1 hour; subsequently, the temperature was increased from 80°C to 550°C at a rate of 4°C / min, holding at this temperature for 2 hours. After natural cooling, the sample was washed three times with deionized water and anhydrous ethanol, respectively, to remove unreacted chemicals. The sample was then dried in a drying oven to obtain TiO2 / C2N prepared by varying the sonication time.
[0060] Compared with the core-shell structure TiO2 / C2N composite material in Example 1, the difference is that the 1 hour of ultrasound is replaced with 10 minutes of ultrasound.
[0061] Transmission electron microscope images of TiO2 / C2N prepared by varying the ultrasonic time are shown below. Figure 3 As shown in (c), a core-shell structure of TiO2 / C2N failed to form. This is because during the mixing stage of HAT-CN and TiO2, insufficient sonication led to severe TiO2 agglomeration, which did not fully expose the active sites, making it difficult for C2N to be uniformly deposited on the TiO2 surface.
[0062] Comparative Example 3: TiO2 / C2N prepared by varying the holding time
[0063] First, 100 mg of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene (HAT-CN) was dispersed in 10 mL of ethanol and sonicated for 1 hour to completely dissolve HAT-CN. Then, 5 g of TiO2 powder was dispersed in the above solution and sonicated for 1 hour followed by magnetic stirring for 12 hours. Next, the mixture was placed in a drying oven to remove the ethanol, yielding the precursor mixture TiO2 / HAT-CN. TiO2 / HAT-CN was placed in a tube furnace purged with argon gas and heated from room temperature to 80°C at a rate of 2°C / min, holding at this temperature for 1 hour; subsequently, the temperature was increased from 80°C to 550°C at a rate of 4°C / min, holding at this temperature for 0.5 hours. After natural cooling, the sample was washed three times with deionized water and anhydrous ethanol, respectively, to remove unreacted chemicals. The sample was then dried in a drying oven to obtain TiO2 / C2N prepared by varying the holding time.
[0064] Compared with the core-shell structure TiO2 / C2N composite material in Example 1, the difference is that the heat preservation time of 2 hours is replaced with heat preservation time of 0.5 hours.
[0065] Transmission electron microscope images of TiO2 / C2N prepared by varying the holding time are shown below. Figure 3 As shown in (d), a core-shell structure of TiO2 / C2N failed to form. This is because during the calcination stage, the gaseous C2N did not diffuse sufficiently to the TiO2 surface, making it difficult for C2N to be uniformly deposited on the TiO2 surface during the cooling stage.
[0066] Comparative Example 4: Preparation of a core-shell structured TiO2 / C3N4 composite material
[0067] First, 100 mg of melamine was dispersed in 10 mL of ethanol and sonicated for 1 hour to completely dissolve HAT-CN. Then, 5 g of TiO2 powder was dispersed in the above solution and magnetically stirred for 12 hours. Next, the mixture was placed in a drying oven to remove the ethanol, yielding the precursor mixture TiO2 / melamine. The TiO2 / melamine was placed in a tube furnace purged with argon gas and heated from room temperature to 80°C at a rate of 2°C / min, holding at that temperature for 1 hour; subsequently, the temperature was increased from 80°C to 550°C at a rate of 4°C / min, holding at that temperature for 2 hours. After natural cooling, the sample was washed three times with deionized water and anhydrous ethanol, respectively, to remove unreacted chemicals. The sample was then dried in a drying oven to obtain a core-shell structured TiO2 / C3N4 composite material.
[0068] The difference from Example 1 is that melamine is replaced with 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene.
[0069] Experimental Example 1
[0070] Experimental materials: the core-shell structured TiO2 / C2N composite material prepared in Example 1 and the TiO2 / C2N prepared in Comparative Example 1.
[0071] NOM was purchased commercially. NOM was dissolved in pure water and filtered through a 0.45μm membrane to prepare a NOM stock solution. NOM solutions of different concentrations were then prepared according to experimental requirements.
[0072] The experimental steps for the photocatalytic selective degradation of novel pollutants by the core-shell structured TiO2 / C2N composite material in this embodiment are as follows:
[0073] Carbamazepine was selected as a novel model pollutant. A 100 mL solution of 5 μM carbamazepine was prepared, and 0, 1, 2, and 5 mg / L NOM were added to the carbamazepine solution. 10 mg of TiO2 / C2N composite material was added and stirred until homogeneous. Simultaneously, a 365 nm UV LED lamp was turned on to begin the degradation experiment. The first-order rate constant (k′) for the degradation of carbamazepine by physically mixed TiO2 / C2N and core-shell structured TiO2 / C2N under UV irradiation in water with NOM concentrations of 0, 1, 2, and 5 mg / L is shown below. Figure 4 As shown in the figure, it is evident that the photocatalytic degradation k′ of carbamazepine by the core-shell structure TiO2 / C2N maintains good stability in the presence of different concentrations of NOM, with k′ decreasing by only 12.1% in water containing 5 mg / L NOM. However, for the physically mixed TiO2 / C2N, its photocatalytic stability is significantly affected by NOM, with k′ decreasing significantly with increasing NOM concentration, decreasing by 69.6% in water containing 5 mg / L NOM. Therefore, this invention can effectively utilize the nanoscale pores of the C2N shell to exclude NOM from the active sites of TiO2 in real water, while allowing new small molecule pollutants to pass through the C2N shell into the active sites of TiO2, thereby rapidly degrading new pollutants without interference from NOM.
[0074] Experimental Example 2
[0075] Experimental materials: the core-shell TiO2 / C2N composite material prepared in Example 1 and the TiO2 / C3N4 core-shell composite material prepared in Comparative Example 4.
[0076] In this example, we used a core-shell TiO2 / C3N4 composite material as a control group to demonstrate the unique advantages of core-shell TiO2 / C2N in the photocatalytic selective degradation of novel pollutants.
[0077] The experimental procedures for the photocatalytic selective degradation of new pollutants by TiO2 / C2N and TiO2 / C3N4 are the same as those in Experiment Example 1.
[0078] Transmission electron microscope images of the core-shell structured TiO2 / C3N4 composite material in this embodiment of the invention are shown below. Figure 5 As shown in (a), the coating of TiO2 by the C3N4 shell can be clearly seen; the elemental mapping image of the composite material is shown in Figure 1. Figure 5 As shown in (b), the successful synthesis of the core-shell structured TiO2 / C3N4 composite material is further demonstrated; the X-ray photoelectron spectrum of the C3N4 shell is as follows. Figure 5 As shown in (c), the CN ratio is 3:4, indicating the successful synthesis of the C3N4 shell.
[0079] In this embodiment of the invention, TiO2 / C2N and TiO2 / C3N4 degrade carbamazepine k′ in water with NOM concentrations of 0, 1, 2, and 5 mg / L under ultraviolet light irradiation. Figure 5 As shown in (d) of the figure, it is evident that the k′ of the TiO2 / C2N photocatalytic degradation of carbamazepine maintains good stability in the presence of different concentrations of NOM, while the photocatalytic stability of TiO2 / C3N4 is significantly affected by NOM. k′ decreases significantly with increasing NOM concentration, decreasing by 57.5% in water containing 5 mg / L NOM. Therefore, this invention demonstrates the unique advantages of TiO2 / C2N in the selective photocatalytic degradation of novel pollutants. It utilizes the nanoscale pores of the C2N shell to exclude NOM from the active sites of TiO2, allowing small-molecule novel pollutants to pass through the C2N shell and enter the active sites of TiO2 for rapid degradation. This invention can significantly suppress the influence of NOM in real water on the photocatalytic degradation of novel pollutants, achieving highly efficient and selective removal of novel pollutants in complex water quality environments.
[0080] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for preparing a core-shell structure TiO2 / C2N composite material, characterized in that, Includes the following steps: 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene HAT-CN was dissolved in ethanol, and TiO2 powder was added. The mixture was sonicated for 0.5-1.5 h, stirred, and dried to obtain the precursor mixture TiO2 / HAT-CN. TiO2 / HAT-CN was calcined in an inert gas atmosphere at 500-600 °C for 1-3 h, then naturally cooled and post-treated to obtain the core-shell structured TiO2 / C2N composite material. The mass ratio of HAT-CN to TiO2 is 1:10~100.
2. The preparation method according to claim 1, characterized in that, The duration of the ultrasound is 1 to 1.5 hours.
3. The preparation method according to claim 1, characterized in that, The specific heating conditions for calcination are as follows: heating from room temperature to 70-90℃ at a heating rate of 1-3℃ / min, and holding at that temperature for 0.5-1.5 h; then heating from 70-90℃ to 500-600℃ at a heating rate of 4℃ / min, and holding at that temperature for 1-3 h.
4. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The concentration of HAT-CN in the ethanol is 5~15 g / L.
5. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The inert gas is argon, helium, or nitrogen.
6. The core-shell structured TiO2 / C2N composite material prepared by any of the preparation methods described in claims 1 to 5.
7. The application of the core-shell structured TiO2 / C2N composite material of claim 6 in the photocatalytic degradation of new pollutants in water.
8. Use according to claim 7, characterized in that, The new pollutants are persistent organic pollutants, endocrine disruptors, and antibiotics.
9. A method for selective degradation of emerging pollutants in water by UV / TiO2 / C2N system, characterized in that, Add the core-shell structured TiO2 / C2N composite material of claim 6 to the water to be treated and stir until homogeneous, while simultaneously turning on the ultraviolet lamp to begin the degradation of new pollutants.