A ternary composite photocatalyst containing carbon quantum dots, its preparation method and application

Abstract

This invention discloses a ternary composite photocatalyst containing carbon quantum dots, its preparation method, and its applications. The ternary composite photocatalyst is prepared in a one-pot process using graphitic carbon nitride, carbon quantum dots, cadmium acetate, zinc acetate, and thiourea via a high-temperature oil bath method. This series of photocatalysts can catalyze the degradation of the antibiotic tetracycline hydrochloride under visible light irradiation; it also catalyzes the depolymerization of lignin and its model compounds under visible light irradiation, exhibiting good stability and reusability. This invention utilizes a one-pot method for photocatalyst preparation, which is simple and convenient to operate; the catalyst possesses excellent photocatalytic performance under visible light; it can efficiently degrade tetracycline hydrochloride under visible light; furthermore, it efficiently catalyzes the conversion of lignin to vanillin, while simultaneously efficiently converting lignin model compounds to aromatic phenolic compounds. This invention offers advantages such as convenient catalyst synthesis, low cost, good stability, high photocatalytic degradation efficiency, and high product selectivity.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, specifically to a ternary composite photocatalyst containing carbon quantum dots, its preparation method, and its application. Background Technology

[0002] With rapid industrial development, fossil resources are becoming increasingly depleted. Lignin, as a naturally abundant renewable aromatic resource, holds promise for replacing fossil resources in the production of high-value-added aromatic products. As a byproduct of the papermaking industry, most lignin is discharged into the environment as waste, causing pollution. Therefore, the value-added utilization of lignin is a crucial scientific research issue. Methods for depolymerizing lignin include acid / base catalysis, biocatalysis, pyrolysis, and metal-catalyzed depolymerization. However, these methods require harsh conditions and significantly damage the aromatic structure of lignin, resulting in low yields of depolymerized aromatic products. Photocatalysis, on the other hand, has attracted attention due to its mild conditions, low cost, and good stability, meeting the requirements of sustainable chemistry.

[0003] Photocatalytic reactions, triggered by light of specific wavelengths, generate excited states that activate reactants and overcome their reaction energy barriers, yielding specific high-value-added chemicals. During a photocatalytic reaction, under light irradiation, electrons in the valence band of a semiconductor photocatalyst transition to the conduction band, forming reducing photogenerated electrons, while the holes left in the valence band possess oxidizing properties. The energy difference between these electrons and holes is the band gap. The design of photocatalysts should consider their appropriate band gap, i.e., the range of light absorption; a narrower band gap allows for a wider absorption wavelength range. Simultaneously, it should consider suppressing the recombination of photogenerated carriers to maintain their redox capabilities. Currently, the construction of heterojunction photocatalysts has attracted widespread attention because, based on energy level matching, they can facilitate the migration of photogenerated electrons and holes from one semiconductor to another, promoting the spatial separation of photogenerated carriers and improving photocatalytic performance.

[0004] g-C3N4, a non-metallic conjugated semiconductor polymer, exhibits excellent chemical stability and is easily synthesized, with a band gap of only 2.7 eV, leading to numerous applications in hydrogen evolution and pollutant degradation. However, its poor utilization of visible light and severe photogenerated electron-hole recombination limit its applications. Carbon quantum dots (CQDs), as carbon nanomaterials, can act as electron migration media, capturing longer wavelengths of light, and due to their surface conjugation and oxygen-containing groups, they are easily combined with other semiconductors. However, CQDs currently suffer from insufficient stability and are easily oxidized and deactivated. CdZnS solid solutions, CdS derivatives, are structures where ZnS and CdS are fused together. Due to their suitable band gap and tunable conduction and valence band positions, they are widely used in solar-driven catalysis. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for preparing a ternary photocatalyst containing carbon quantum dots.

[0006] The second objective of this invention is to provide a ternary composite photocatalyst prepared by the above-mentioned method.

[0007] The third objective of this invention is to provide the application of the above-mentioned ternary composite photocatalyst in the efficient degradation of tetracycline hydrochloride under visible light.

[0008] The fourth objective of this invention is to provide the application of ternary composite photocatalysts in the catalytic conversion of lignin and its model compounds into aromatic compounds under visible light.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides a method for preparing a ternary composite photocatalyst containing carbon quantum dots, comprising the following steps:

[0011] 1) Disperse g-C3N4 and carbon quantum dots in deionized water by ultrasonication, then dissolve cadmium acetate dihydrate and zinc acetate dihydrate in the mixture, and then slowly add thiourea solution and ethylene glycol. React in a high-temperature oil bath.

[0012] 2) After the reaction is complete, the mixture is rapidly cooled to room temperature, filtered, washed with water and ethanol in sequence, and dried under vacuum to obtain a Z-type ternary composite catalyst containing carbon quantum dots, g-C3N4 and zinc-cadmium sulfur.

[0013] Preferably, in step 1), the mass ratio of g-C3N4 to cadmium acetate dihydrate is 1:22 to 1:2.2, and the mass ratio of g-C3N4 to carbon quantum dots is 1:0.5 to 1:5.

[0014] Preferably, in step 1), the molar ratio of cadmium acetate dihydrate, zinc acetate dihydrate, and thiourea is 1:1:2 to 4.

[0015] Preferably, in step 1), the heating temperature is 120-130°C, the heating and stirring time is 8-12 hours, and the heating and stirring speed is 500-600 r / min.

[0016] Secondly, the present invention provides a ternary composite photocatalyst prepared by the above-described preparation method.

[0017] Thirdly, the present invention provides the application of the above-mentioned ternary composite photocatalyst in the degradation of tetracycline hydrochloride under visible light.

[0018] The specific steps include: 1.1) Placing the ternary composite photocatalyst and tetracycline hydrochloride aqueous solution in the photoreactor, with the amount of photocatalyst being 1 g / L, first ultrasonically dispersing for 10-15 min, then stirring in the dark for 25-35 min; carrying out the degradation reaction under normal temperature and pressure and visible light irradiation, with a degradation time of 40-120 min and a rotation speed of 300-400 r / min;

[0019] 1.2) After the reaction is completed, the reaction solution is filtered, and the filtrate is sampled for UV-vis detection. The solid is washed with deionized water and ethanol in sequence, and then vacuum dried to recover the catalyst.

[0020] Fourthly, this invention provides the application of the above-mentioned ternary composite photocatalyst in the catalytic depolymerization of lignin and model compounds under visible light to prepare vanillin.

[0021] The specific steps include: 2.1) Mixing the ternary composite photocatalyst and lignin or lignin model compound in a solvent and then placing it in a photoreactor, first ultrasonically dispersing for 10-15 min, then stirring in the dark for 25-35 min; stirring and reacting at room temperature and pressure and visible light irradiation for 0.5-3 h, with a rotation speed of 300-400 r / min; the mass ratio of the photocatalyst to lignin is 1-2:1, and the mass ratio of the photocatalyst to the lignin model compound is 1-3:1;

[0022] 2.2) After the reaction is completed, the reaction solution is filtered, the filtrate is sampled and analyzed by HPLC, the solid is washed with deionized water and ethanol, vacuum dried, and the catalyst is recovered.

[0023] Preferably, in step 2.1), the solvent is a mixed solvent of sodium dodecyl sulfate aqueous solution and formic acid, wherein the concentration of the sodium dodecyl sulfate aqueous solution is 0.08%. wt % ~ 0.12 wt The volume ratio of sodium dodecyl sulfate aqueous solution to formic acid is 7-9:3-1.

[0024] Preferably, in step 2.1), the lignin model compounds participate in the reaction under the protection of an inert gas.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention utilizes the strong electron-trapping capability of CQDs combined with the visible light absorption capabilities of g-C3N4 and CdZnS to prepare a Z-type heterojunction photocatalyst in a one-pot oil bath process. By stirring and adsorbing the synthesized composite photocatalyst onto tetracycline hydrochloride wastewater, followed by degradation under visible light, it can efficiently photocatalytically degrade tetracycline hydrochloride in wastewater. This method offers advantages such as simple operation, environmental friendliness, mild reaction conditions, and high removal efficiency, resulting in greater economic benefits compared to existing technologies.

[0027] 2. The photocatalyst prepared by this invention can produce vanillin in one step, utilizing renewable light energy without the need for additional high temperature and high pressure, thus improving the safety of the process. At the same time, the use of surfactant aqueous solution avoids the use of strong acids and alkalis, which is in line with the concept of sustainable development.

[0028] 3. The photocatalyst prepared by this invention can significantly improve the yield of lignin model compounds to phenolic monomers under visible light. Since the reaction is carried out at room temperature and pressure, the problem of repolymerization of phenolic monomers is avoided.

[0029] 4. The catalyst is simple to synthesize, has good stability, and can be recycled multiple times after simple treatment. Attached Figure Description

[0030] Figure 1 The flowchart shows the preparation of photocatalysts, the degradation of tetracycline hydrochloride, and the catalysis of lignin and its model compounds.

[0031] Figure 2 The infrared spectrum of the photocatalyst 5CQDs / 25CCZS;

[0032] Figure 3 XRD pattern of photocatalyst 5CQDs / 10CCZS;

[0033] Figure 4 The image shows the reproducibility of the photocatalyst 5CQDs / 25CCZS for the degradation of tetracycline hydrochloride.

[0034] Figure 5 Reproducibility of vanillin preparation from lignin using 5CQDs / 10CCZS photocatalyst. Detailed Implementation

[0035] The following detailed embodiments are used to illustrate the present invention, but should not be construed as limiting the invention to these embodiments. The reagents and instruments used in the following embodiments are all commercially available.

[0036] The following is in accordance with Figure 1 The flowchart shown illustrates the preparation of photocatalysts and their degradation of tetracycline hydrochloride and catalytic lignin and its model compounds, providing a detailed description of the present invention.

[0037] This invention uses a UV-Vis spectrophotometer (TU-1901, Beijing Purkinje, China) to detect the absorbance change of tetracycline hydrochloride at 360 nm. The degradation rate of tetracycline hydrochloride = (1-A) t / A0)×100%; where A t A represents the absorbance at 360 nm at time t, and A0 represents the change in absorbance at 360 nm at the beginning.

[0038] This invention uses HPLC analysis to detect the conversion rates of vanillin and lignin model compounds and the yields of phenolic monomers in the reaction. The analytical conditions are as follows:

[0039] An Agilent 1260 high-performance liquid chromatograph with an Agilent Eclipse Plus C18 column (5μm×4.6×250mm), a diode array detector, a flow rate of 0.6mL / min, a column temperature of 35℃, and a detection wavelength of 280nm was used.

[0040] Qualitative and quantitative analyses of vanillin, β-O-4 type lignin model compounds, and phenol were obtained using standard curves. Vanillin yield (mg / g) = m 香兰素 / m 木质素 , 1a conversion rate = (1-M f / M i )×100%, Phenolic monomer yield = M p / M i ×100%; where M f M represents the number of moles of the lignin model compound after the reaction is complete. i M represents the initial molar number of the lignin model compound in the reaction. p This indicates the number of moles of phenolic monomers after the reaction is complete.

[0041] Example 1

[0042] A ternary photocatalyst containing carbon quantum dots was prepared by the following steps: 0.12 g of graphitic carbon nitride (g-C3N4) and 10 mL of CQDs solution (40 g / L) were dispersed in 30 mL of water in a single-necked flask. The mixture was sonicated in an ultrasonic-microwave reactor for 30 min. Then, 2 mmol of cadmium acetate dihydrate and 2 mmol of zinc acetate dihydrate were added sequentially, followed by 10 mL of ethylene glycol. The mixture was stirred for 10 min at a speed of 500–600 r / min. Next, 30 mL of thiourea solution (20 g / L) was added dropwise. The reaction was carried out at 120 °C with stirring for 8 h. After the reaction was complete, the reactor was cooled to room temperature in an ice-water bath. The reaction system was removed and filtered. The solid was washed multiple times with deionized water and ethanol, respectively. The solid was then dried in a vacuum drying oven at 60 °C for 6 h.

[0043] The g-C3N4 can be prepared from urea and melamine. The specific preparation method is as follows: urea and melamine are mixed at a mass ratio of 4:1, ground, compacted, and then placed in a muffle furnace. The temperature is increased to 550°C at 5°C / min, and calcined for 3 hours to obtain g-C3N4.

[0044] When preparing the catalyst, let the volume of CQDs added be x, and the amount of g-C3N4 added be y. The prepared ternary composite catalyst is labeled as xCQDs / yCCZS.

[0045] Figure 2 The image shows the infrared spectrum of the photocatalyst 5CQDs / 25CCZS. The characteristic peaks in g-C3N4 are between 1241 and 1640 cm⁻¹. -1 and 810cm -1 The stretching vibrations correspond to the g-C3N4 heterocyclic structure and the s-triazine stacked structure; 5CQDs / 25CCZS contains obvious g-C3N4 characteristic peaks.

[0046] Figure 3 The XRD pattern of the prepared photocatalyst 5CQDs / 10CCZS is shown, revealing distinct diffraction planes of g-C3N4 and CdZnS. The 26.5° peak of g-C3N4 is attributed to the (002) plane resulting from the layered stacking structure. Furthermore, the peaks at 25.0°, 26.6°, 28.4°, 43.9°, 47.8°, and 52.1° are characteristic diffraction peaks of ZnS and CdS, respectively, belonging to the (100), (002), (111), (110), (102), and (112) planes. Upon the addition of CQDs, the (002) peak intensity is significantly enhanced due to the π-π superposition effect of CQDs and g-C3N4. IR and XRD results confirm that the catalyst of this invention is a ternary composite material of CQDs, CdS, and g-C3N4.

[0047] Comparative Example 1

[0048] The preparation steps are the same as in Example 1, except that CQDs are not added, resulting in a g-C3N4 / CdZnS composite catalyst, and y% g-C3N4 / CdZnS is named yCCZS.

[0049] Comparative Example 2

[0050] 100 mL of deionized water and 3 mg of tetracycline hydrochloride were added to the photoreactor. 100 mg of 5CCZS was weighed and added to the system. The mixture was sonicated for 10 min in the dark and then stirred for 30 min. After irradiation with a light source for 1 h at room temperature and pressure, samples were taken and detected by a UV-Vis spectrophotometer. The degradation rate of tetracycline hydrochloride was 76.6%. The catalyst was washed with deionized water / ethanol and dried.

[0051] Comparative Example 3

[0052] 100 mL of deionized water and 3 mg of tetracycline hydrochloride were added to the photoreactor. 100 mg of 10 CCZS was weighed and added to the system. The mixture was sonicated for 10 min in the dark and then stirred for 30 min. After irradiation with a light source at room temperature and pressure for 100 min, a sample was taken and detected by a UV-Vis spectrophotometer. The degradation rate of tetracycline hydrochloride was 78%. The mixture was then filtered, and the catalyst was washed with deionized water / ethanol and dried.

[0053] Comparative Example 4

[0054] 100 mL of deionized water and 3 mg of tetracycline hydrochloride were added to a glass reactor. 100 mg of 25 CCZS was weighed and added to the system. The mixture was sonicated for 10 min in the dark and then stirred for 30 min. After irradiation with a light source at room temperature and pressure for 100 min, a sample was taken and detected by a UV-Vis spectrophotometer. The degradation rate of tetracycline hydrochloride was 82%. The mixture was then filtered, and the catalyst was washed with deionized water / ethanol and dried.

[0055] Comparative Example 5

[0056] 100 mL of deionized water and 3 mg of tetracycline hydrochloride were added to a glass reactor. 100 mg of 50 CCZS was weighed and added to the system. The mixture was sonicated for 10 min in the dark and then stirred for 30 min. After irradiation with a light source at room temperature and pressure for 100 min, a sample was taken and detected by a UV-Vis spectrophotometer. The degradation rate of tetracycline hydrochloride was 79.2%. The mixture was then filtered, and the catalyst was washed with deionized water / ethanol and dried.

[0057] Example 2

[0058] 100 mL of deionized water and 3 mg of tetracycline hydrochloride were added to a glass reactor. 100 mg of 1 CQDs / 25 CCZS was weighed and added to the system. The mixture was sonicated for 10 min in the dark and then stirred for 30 min. After irradiation with a light source at room temperature and pressure for 100 min, a sample was taken and detected by a UV-Vis spectrophotometer. The degradation rate of tetracycline hydrochloride was 88%. The mixture was then filtered, and the catalyst was washed with deionized water / ethanol and dried.

[0059] Example 3

[0060] 100 mL of deionized water and 4 mg of tetracycline hydrochloride were added to a glass reactor. 100 mg of 5CQDs / 25CCZS was weighed and added to the system. The mixture was sonicated for 10 min in the dark and then stirred for 30 min. After irradiation with a light source at room temperature and pressure for 100 min, a sample was taken and detected by a UV-Vis spectrophotometer. The degradation rate of tetracycline hydrochloride was 93.3%. The mixture was then filtered, and the catalyst was washed with deionized water / ethanol and dried.

[0061] Example 4

[0062] 100 mL of deionized water and 3 mg of tetracycline hydrochloride were added to a glass reactor. 100 mg of 10 CQDs / 25 CCZS was weighed and added to the system. The mixture was sonicated for 10 min in the dark and then stirred for 30 min. After irradiation with a light source at room temperature and pressure for 100 min, a sample was taken and detected by a UV-Vis spectrophotometer. The degradation rate of tetracycline hydrochloride was 90%. The mixture was then filtered, and the catalyst was washed with deionized water / ethanol and dried.

[0063] Table 1 Comparison of data on the degradation of tetracycline hydrochloride by different photocatalysts with that of the present invention

[0064]

[0065]

[0066] As shown in Table 1, the photocatalyst 5CQDs / 25CCZS of this invention exhibits significant advantages compared to previously reported catalysts. Under high-concentration tetracycline hydrochloride conditions, it not only demonstrates a shorter degradation time but also achieves a degradation rate of 93.3%, exhibiting superior catalytic performance. Furthermore, compared to the comparative example g-C3N4 / CdZnS, it significantly shortens the degradation time and accelerates the degradation rate, which is attributed to the powerful electron storage capacity of CQDs. The addition of CQDs can capture photogenerated electrons, improving the separation efficiency of photogenerated electrons and holes. There is a synergistic effect among g-C3N4, CQDs, and CdZnS.

[0067] A certain amount of dried 5CQDs / 25CCZS photocatalyst was repeatedly subjected to experiments degrading tetracycline hydrochloride to investigate the stability of the catalyst. The results are as follows: Figure 4 As shown in the figure, 5CQDs / 25CCZS can effectively catalyze the degradation of tetracycline hydrochloride under visible light, and maintains a high degradation rate even during repeated testing. This indicates that the g-C3N4 / 5CQDs / CdZnS photocatalyst exhibits sufficient catalytic stability in the cyclic test, thus solving the problem of poor stability of CQDs.

[0068] Example 5

[0069] Add 5 mg of 5CQDs / 10CCZS, along with 5 mg of lignin and 5 mL of solvent (5 mL 0...) to the photoreactor. wt The vanillin solution was ultrasonicated for 10 min in the dark, then stirred for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 2 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80℃ for 6 h for later use. The vanillin yield was 13.6 mg / g.

[0070] Example 6

[0071] Add 5 mg of 5CQDs / 10CCZS, along with 5 mg of lignin and 5 mL of solvent (5 mL 0.04...) to the photoreactor. wt The vanillin solution was ultrasonicated for 10 min in the dark, then stirred for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 2 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80℃ for 6 h for later use. The yield of vanillin was 15.1 mg / g.

[0072] Example 7

[0073] Add 5 mg of 5CQDs / 10CCZS, along with 5 mg of lignin and 5 mL of solvent (5 mL 0.08...) to the photoreactor. wt The vanillin solution was ultrasonicated for 10 min in the dark, then stirred for 30 min. The light source was then turned on, and the reaction was carried out at room temperature and atmospheric pressure for 2 h under visible light irradiation. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80℃ for 6 h for later use. The vanillin yield was 18 mg / g.

[0074] Example 8

[0075] Add 5 mg of 5CQDs / 10CCZS, along with 5 mg of lignin and 5 mL of solvent (5 mL 0.12...) to the photoreactor. wt The vanillin solution was ultrasonicated for 10 min in the dark, then stirred for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 2 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80℃ for 6 h for later use. The yield of vanillin was 14.5 mg / g.

[0076] Example 9

[0077] 5 mg of 5CQDs / 10CCZS, along with 5 mg of lignin and 5 mL of solvent (4.5 mL 0.08 g / L), were added to the photoreactor. wt The mixture was sonicated for 10 min under light-protected conditions (using % SDS aqueous solution and 0.5 mL formic acid solution), then stirred for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 2 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80 °C for 6 h for later use. The vanillin yield was 17.9 mg / g.

[0078] Example 10

[0079] 5 mg of 5CQDs / 10CCZS, along with 5 mg of lignin and 5 mL of solvent (4.0 mL 0.08 g / L), were added to the photoreactor. wt The mixture was ultrasonicated for 10 min in the dark (using % SDS aqueous solution and 1.0 mL formic acid solution), then stirred for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 2 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80℃ for 6 h for later use. The vanillin yield was 24.9 mg / g.

[0080] Example 11

[0081] 5 mg of 5CQDs / 10CCZS, along with 5 mg of lignin and 5 mL of solvent (3.5 mL 0.08 g / L), were added to the photoreactor. wt The mixture was sonicated for 10 min under light-protected conditions (using % SDS aqueous solution and 1.5 mL formic acid solution), then stirred for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 2 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80 °C for 6 h for later use. The vanillin yield was 18.6 mg / g.

[0082] Comparative Example 6

[0083] 5 mg of 10 CCZS, along with 5 mg of lignin and 5 mL of solvent (4.0 mL 0.08 g / L), were added to the photoreactor. wt The mixture was sonicated for 10 min under light-protected conditions (using % SDS aqueous solution and 1.0 mL formic acid solution), then stirred for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 2 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80℃ for 6 h for later use. The vanillin yield was 19.3 mg / g.

[0084] Table 2 Comparison of vanillin yields from lignin prepared by different photocatalysts with those of the present invention.

[0085]

[0086] As shown in Table 2, the vanillin yield of the 5CQDs / 10CCZS photocatalyst of this invention is higher than that of previously reported catalysts under visible light catalysis, exhibiting advantages such as low catalyst concentration and catalysis under visible light. Furthermore, compared to the comparative g-C3N4 / CdZnS, the vanillin yield is improved under the same catalytic conditions, which is attributed to the strong electron capture and storage capabilities of CQDs. The addition of CQDs promotes the separation of photogenerated electrons and holes, enhancing the catalytic activity of the photocatalyst. There is a synergistic enhancing effect among g-C3N4, CQDs, and CdZnS.

[0087] Example 12

[0088] Add 5 mg of 5CQDs / 10CCZS to the photoreactor, along with 5 mg of 1a and 5 mL of solvent (3.5 mL 0.08). wt The mixture was prepared with 1% SDS aqueous solution and 1.5 mL formic acid solution, under a protected N2 atmosphere, and then sonicated for 10 min in the dark, followed by stirring for 30 min. The light source was then turned on, and the reaction was carried out under visible light irradiation at room temperature and atmospheric pressure for 1.5 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80 °C for 6 h for later use. The conversion rate of 1a was 84%, the yield of phenol was 60%, and the yield of acetophenone was 63%.

[0089]

[0090] Example 13

[0091] Add 5 mg of 5CQDs / 10CCZS to the photoreactor, along with 5 mg of 2a and 5 mL of solvent (3.5 mL 0.08). wt The mixture was prepared with 1% SDS aqueous solution and 1.5 mL formic acid solution, under a protected N2 atmosphere, and then sonicated for 10 min in the dark, followed by stirring for 30 min. The light source was then turned on, and the reaction was carried out under visible light at room temperature and atmospheric pressure for 1.5 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80 °C for 6 h for later use. The conversion rate of 2a was 80%, the yield of phenol was 50%, and the yield of acetophenone was 40%.

[0092]

[0093] Example 14

[0094] Add 5 mg of 5CQDs / 10CCZS to the photoreactor, along with 5 mg of 1b and 5 mL of solvent (3.5 mL 0.08). wt The mixture was prepared with 1% SDS aqueous solution and 1.5 mL formic acid solution, under a protected N2 atmosphere, and then sonicated for 10 min in the dark, followed by stirring for 30 min. The light source was then turned on, and the reaction was carried out under visible light irradiation at room temperature and atmospheric pressure for 1.5 h. After the reaction was complete, the mixture was filtered, the solid was washed with acetonitrile, and the filtrate was analyzed by HPLC. The solid was dried in an oven at 80 °C for 6 h for later use. The conversion rate of 1b was 28.9%, the yield of phenol was 12%, and the yield of acetophenone was 11.8%.

[0095]

[0096] References

[0097] [1]Jiang D, Xiao P, Shao L, et al. RGO-promoted all-solid-state g-C3N4 / BiVO4 Z-scheme heterostructure with enhanced photocatalytic activity toward the degradation of antibiotic[J]. Industrial&Engineering Chemistry Research, 2017,56:8823-8832

[0098] [2]Xu J,Li M,Qiu J et al.PEGylated deep eutectic solvent-assistedsynthesis of CdS@CeO2 composites with enhanced visible light photocatalyticability[J].Chemical Engineering Journal,2020,383:123135.

[0099] [3]Jiang E,Song N,Che G,et al.Construction of a Z-scheme MoS2 / CaTiO3heterostructure by the morphology-controlled strategy towards enhancingphotocatalytic activity[J].Chemical Engineering Journal,2020,399:125721.

[0100] [4]Zhu Z,Xia H,Li H.Boosting photocatalytic degradation efficiency oftetracycline by a visible-light-activated NiMoO4 / g-C3N4 heterojunctionphotocatalyst in the water environment[J].Solid State Sciences,2023,139:107164.

[0101] [5]Zhang S,Khan I,Qin X,et al.Sonochemical Construction of 1D Ag-AgBr / AlOOH Plasmonic Photocatalyst for Degradation of TetracyclineHydrochloride[J].Frontiers in Chemistry,2020,8:117.

[0102] [6]Luo B F,Chen M,Zhang Z Y,et al.Highly efficient visible-light-driven photocatalytic degradation of Tetracycline by a Z-Scheme g-C3N4 / Bi3TaO7nanocomposite photocatalyst[J].Dalton Transactions,2017,46,8431-8438.

[0103] [7]Prado R,Erdocia X,Labidi J.Effect of the photocatalytic activityof TiO2 on lignin depolymerization[J].Chemosphere,2013,91(9):1355-1361.

[0104] [8]Qiu J,Dai D,Zhang L,et al.Photocatalytic conversion of sodiumlignosulfonate into vanillin using mesoporous TiO2 derived from MIL-125[J].Microporous and Mesoporous Materials,2021,319:111043.

[0105] [9]Gong J,Imbault A,Farnood R.The promoting role of bismuth for theenhanced photocatalytic oxidation of lignin on Pt-TiO2 under solar lightillumination[J].Applied Catalysis B-Environmental,2017,204:296-303.

[0106]

[10] Du Z,Li W,Xu Z,et al.Characterization Of C-60 / Bi2TiO4F2 as aPotential Visible Spectrum Photocatalyst for The Depolymerization of Lignin[J].Journal of Wood Chemistry and Technology,2016,36(5):365-376.

[0107]

[11] Liu H,Li H,Luo N,et al.Visible-Light-Induced Oxidative Lignin C-CBond Cleavage to Aldehydes Using Vanadium Catalysts[J].ACS Catalysis,2020,10(1):632-643.

[0108]

[12] Cui M,Liang C,Zhao W,et al.Fabrication of Z-scheme CdS / H5PMo 10 V2O 40 / g-C3N4 for the photocatalytic depolymerization of lignin intoaromatic monomers[J].Fuel Processing Technology,2022,238:107481.

[0109]

[13] Srisasiwimon N,Chuangchote S,Laosiripojana N,et al.TiO2 / Lignin-Based Carbon Composited Photocatalysts for Enhanced Photocatalytic Conversionof Lignin to High Value Chemicals[J].ACS Sustainable Chemistry&Engineering,2018,6(11):13968-13976.

[0110] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. Use of ternary composite photocatalyst in the degradation of tetracycline hydrochloride under visible light, characterized in that, The ternary composite photocatalyst is prepared by the following steps: 1) Disperse g-C3N4 and carbon quantum dots in deionized water by ultrasonication, then dissolve cadmium acetate dihydrate and zinc acetate dihydrate in the mixture, and then slowly add thiourea solution and ethylene glycol. Stir the reaction at 120~130 ℃ for 8~12 h with a stirring speed of 500~600 r / min. 2) After the reaction is complete, the mixture is rapidly cooled to room temperature, filtered, washed with water and ethanol in sequence, and dried under vacuum to obtain a Z-type ternary composite catalyst containing carbon quantum dots, g-C3N4 and zinc-cadmium sulfur.

2. Use according to claim 1, characterized in that, The degradation method includes: placing a ternary composite photocatalyst and a tetracycline hydrochloride aqueous solution in a photoreactor, with the amount of photocatalyst being 1 g / L, first ultrasonically dispersing for 10-15 min, and then stirring in the dark for 25-35 min; the degradation reaction is carried out under normal temperature and pressure and visible light irradiation.

3. Application of ternary composite photocatalyst in catalyzing depolymerization of lignin and model compound to prepare vanillin under visible light, characterized in that, The ternary composite photocatalyst is prepared by the following steps: 1) Disperse g-C3N4 and carbon quantum dots in deionized water by ultrasonication, then dissolve cadmium acetate dihydrate and zinc acetate dihydrate in the mixture, and then slowly add thiourea solution and ethylene glycol. Stir the reaction at 120~130 ℃ for 8~12 h with a stirring speed of 500~600 r / min. 2) After the reaction is complete, the mixture is rapidly cooled to room temperature, filtered, washed with water and ethanol in sequence, and dried under vacuum to obtain a Z-type ternary composite catalyst containing carbon quantum dots, g-C3N4 and zinc-cadmium sulfur.

4. The application according to claim 3, characterized in that, The catalytic method includes: mixing a ternary composite photocatalyst and lignin or a lignin model compound in a solvent and then placing the mixture in a photoreactor, wherein the mass ratio of the photocatalyst to lignin is 1~2:1 and the mass ratio of the photocatalyst to the lignin model compound is 1~3:1; first ultrasonically dispersing for 10~15 min, then stirring in the dark for 25~35 min; the autogenous temperature of the reaction system is 30~40℃, and the reaction is carried out under ambient temperature, ambient pressure and visible light irradiation.

5. The application according to claim 4, characterized in that, The solvent is a mixture of sodium dodecyl sulfate aqueous solution and formic acid, wherein the concentration of sodium dodecyl sulfate aqueous solution is 0.08wt%-0.12wt%, and the volume ratio of sodium dodecyl sulfate aqueous solution to formic acid is 7~9:3~1.

6. The application according to claim 1 or 3, characterized in that, In step 1), the mass ratio of g-C3N4 to cadmium acetate dihydrate is 1:22 to 1:2.2, and the mass ratio of g-C3N4 to carbon quantum dots is 1:5 to 1:0.

5.

7. The application according to claim 1 or 3, characterized in that, In step 1), the molar ratio of cadmium acetate dihydrate, zinc acetate dihydrate, and thiourea is 1:1:2~4.

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