Manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst and preparation method and application thereof
Through the use of manganese-doped carbon quantum dot/molybdenum oxide composite photocatalyst, the problem of difficult degradation of cephalosporin antibiotics is solved, and an efficient, economical and environmentally friendly degradation effect is achieved. The catalyst has good stability and reusability.
Patent Information
- Application Number
- CN202510277475.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-05-13
AI Technical Summary
The prior art is difficult to effectively degrade residual cephalosporin antibiotics in the environment, and the existing degradation methods have problems such as high cost and complex operation.
The composite photocatalyst was prepared by a two-step hydrothermal synthesis method using a manganese-doped carbon quantum dot/molybdenum oxide composite photocatalyst, and its efficient photocatalytic activity was used to degrade cephalosporin antibiotics.
It has achieved efficient degradation of cephalosporin antibiotics, with a degradation rate of up to 87.4%, and the composite photocatalyst has good stability and reusability, and the preparation method is simple and the cost is low.
Smart Images
Figure CN119972136A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of antibiotic degradation, and specifically relates to a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst and a preparation method and application thereof. Background Art
[0002] Cephalosporin antibiotics are a class of β-lactam antibiotics widely used in clinical treatment. They have the characteristics of broad antibacterial spectrum, strong antibacterial effect, and penicillinase resistance. With the rapid development of the medical and aquaculture industries, the use of cephalosporin antibiotics has continued to increase, and the problem of their residues in the environment has become increasingly prominent. These antibiotics enter the environment through medical wastewater, aquaculture wastewater and other channels, which may pose a potential threat to the ecosystem and human health.
[0003] Cephalosporin antibiotics have a complex chemical structure, high biological toxicity and environmental persistence. Its core structure is a β-lactam ring, and the stability of this ring makes cephalosporin antibiotics difficult to degrade naturally in the environment. Traditional wastewater treatment methods, such as biological treatment, often have difficulty in effectively removing cephalosporin antibiotics because their high antibacterial properties can cause the death of microorganisms in the biological treatment system.
[0004] In recent years, studies have found that some microorganisms and chemical methods can be used to degrade cephalosporin antibiotics. For example, some strains such as Proteus sp. CW-1 and Galactomyces candidum CM1 have been found to have the ability to degrade cephalosporin antibiotics. These microorganisms can decompose cephalosporin antibiotics into small molecules through specific enzyme systems or metabolic pathways, thereby reducing their toxicity. In addition, chemical methods such as electrocatalytic degradation and photocatalytic degradation have also shown good degradation effects.
[0005] However, the existing degradation technology still has some shortcomings. For example, some microbial degradation strains have limited tolerance to high concentrations of antibiotics, and the degradation efficiency needs to be improved; while chemical degradation methods may face problems such as high cost and complex operation. Therefore, the development of efficient, economical and environmentally friendly cephalosporin antibiotic degradation technology is of great practical significance. Summary of the invention
[0006] Based on the above-mentioned prior art, the present invention provides a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst and its preparation method and application. The composite photocatalyst of the present invention has high photocatalytic activity, can improve the photocatalytic degradation effect of cephalosporin antibiotics, can be reused, has high stability, and has a simple preparation method and low preparation cost.
[0007] The technical solution adopted to achieve the above-mentioned purpose of the present invention is:
[0008] A method for preparing a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst comprises the following steps:
[0009] S1. Dissolve urea, glucose and manganese source in deionized water, stir and dissolve to obtain a precursor solution;
[0010] S2, transferring the precursor solution to a reactor, performing a hydrothermal reaction at 160-200°C for 6-16h, cooling to room temperature after the reaction, centrifuging, dialyzing the supernatant, and drying to obtain manganese-doped carbon quantum dots;
[0011] S3, dissolving a molybdenum source in deionized water to obtain a molybdenum source solution, adding manganese-doped carbon quantum dots and anionic surfactant to the molybdenum source solution, stirring and dissolving, and obtaining a mixed solution;
[0012] S4. The mixed solution is transferred to a reactor and subjected to a hydrothermal reaction at 180-220°C for 12-24 hours. After the reaction is completed, the mixed solution is cooled to room temperature, filtered, washed, and dried to obtain a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst.
[0013] Furthermore, the manganese source is selected from manganese sulfate, manganese chloride or manganese acetate.
[0014] Furthermore, the mass ratio of urea, glucose and manganese source is 5:4-6:1-3.
[0015] Furthermore, the molybdenum source is selected from sodium molybdate or ammonium molybdate.
[0016] Furthermore, the anionic surfactant is selected from sodium dodecyl sulfate or sodium dodecylbenzene sulfonate.
[0017] Furthermore, the mass ratio of the manganese-doped carbon quantum dots, the molybdenum source and the anionic surfactant is 1:10-20:1-3.
[0018] A manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst prepared by any of the above methods.
[0019] Application of a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst in the degradation of cephalosporin antibiotics.
[0020] Furthermore, the cephalosporin antibiotic is ceftriaxone sodium.
[0021] Compared with the prior art, the advantages and beneficial effects of the present invention are:
[0022] 1. In the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst of the present invention, both manganese-doped carbon quantum dots (Mn-CQDs) and molybdenum oxide (MoO3) have good light absorption properties, especially Mn-CQDs can extend the light absorption range to the visible light region, thereby improving the photocatalytic efficiency.
[0023] 2. In the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst of the present invention, manganese, CQDs and MoO3 work synergistically to greatly improve the photocatalytic performance of the composite photocatalyst. Mn-doped carbon quantum dots enhance light absorption and charge separation efficiency, while MoO3 provides abundant active sites and a stable catalytic environment. The manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst generates and separates photogenerated electron-hole pairs to produce highly oxidizing active oxygen species, thereby achieving efficient degradation of cephalosporin antibiotics.
[0024] 3. The manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst of the present invention has good photocatalytic activity and good photocatalytic effect on cephalosporin antibiotics, and the composite photocatalyst can be reused and has high stability. Experiments show that the degradation rate of ceftriaxone sodium by the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst of the present invention is as high as 87.4%.
[0025] 4. The manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst of the present invention can be prepared by a two-step hydrothermal synthesis method. The preparation method is simple and easy to operate, and the preparation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is the TEM image of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared in Example 1.
[0027] Figure 2 This is a diagram showing the degradation effect of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared in Example 1-3 on ceftriaxone sodium.
[0028] Figure 3 This is a diagram showing the effect of cyclic degradation of ceftriaxone sodium by the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared in Example 1. DETAILED DESCRIPTION
[0029] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the implementation examples described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.
[0030] Example 1
[0031] 1. Weigh 0.75 g urea, 0.75 g glucose and 0.3 g manganese sulfate, add urea and manganese sulfate to 30 ml deionized water, stir and dissolve to obtain a precursor solution;
[0032] 2. Transfer the precursor solution to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) to ensure that the reactor is well sealed. Heat the reactor to 180°C and keep it at 180°C for 12 hours. After the reaction is completed, cool it naturally to room temperature, centrifuge the resulting mixed product, dialyze the supernatant with an 8kDa dialysis bag (dialysis fluid is deionized water) for 24 hours, collect the solution in the dialysis bag and freeze-dry it to obtain manganese-doped carbon quantum dots, labeled as Mn-CQDs-I;
[0033] 3. Weigh 1g of sodium molybdate and add it to 60mL of deionized water, stir until completely dissolved to obtain a sodium molybdate solution;
[0034] 4. Weigh 0.08 g of manganese-doped carbon quantum dots and 0.2 g of sodium dodecyl sulfate, add manganese-doped carbon quantum dots and sodium dodecyl sulfate to the sodium molybdate solution, respectively, and stir until completely dissolved to obtain a mixed solution;
[0035] 5. Transfer the mixed solution to a reactor with a polytetrafluoroethylene (PTFE) liner, heat the reactor to 200°C, and keep the reaction at 200°C for 18 hours. After the reaction is completed, cool it naturally to room temperature, filter the obtained mixed product, wash the filter cake with deionized water and ethanol alternately for 3 times, and then dry it at 60°C for 8 hours to obtain a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst, marked as Mn-CQDs / MoO3-I.
[0036] The TEM image of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared in this example is shown in FIG. Figure 1 As shown by Figure 1 It can be seen that the spherical manganese-doped carbon quantum dot nanoparticles (about 3 nm) are uniformly dispersed on the surface of the molybdenum oxide nanosheets or embedded in the interlayer. The manganese-doped carbon quantum dots form a heterojunction with molybdenum oxide, which promotes the separation of photogenerated carriers and improves the photocatalytic activity.
[0037] Example 2
[0038] 1. Weigh 0.75 g urea, 0.75 g glucose and 0.15 g manganese sulfate, add urea and manganese sulfate to 30 ml deionized water, stir and dissolve to obtain a precursor solution;
[0039] 2. Transfer the precursor solution to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) to ensure that the reactor is well sealed. Heat the reactor to 160°C and keep it at 160°C for 16 hours. After the reaction is completed, cool it naturally to room temperature, centrifuge the resulting mixed product, dialyze the supernatant with an 8kDa dialysis bag (dialysis fluid is deionized water) for 24 hours, collect the solution in the dialysis bag and freeze-dry it to obtain manganese-doped carbon quantum dots, labeled as Mn-CQDs-II;
[0040] 3. Weigh 1g of sodium molybdate and add it to 60mL of deionized water, stir until completely dissolved to obtain a sodium molybdate solution;
[0041] 4. Weigh 0.05 g of manganese-doped carbon quantum dots and 0.3 g of sodium dodecyl sulfate, add manganese-doped carbon quantum dots and sodium dodecyl sulfate to the sodium molybdate solution, respectively, and stir until completely dissolved to obtain a mixed solution;
[0042] 5. Transfer the mixed solution to a reactor with a polytetrafluoroethylene (PTFE) liner, heat the reactor to 200°C, and keep the reaction at 180°C for 24 hours. After the reaction is completed, cool it naturally to room temperature, filter the obtained mixed product, wash the filter cake with deionized water and ethanol alternately for 3 times, and then dry it at 60°C for 8 hours to obtain a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst, marked as Mn-CQDs / MoO3-II.
[0043] Example 3
[0044] 1. Weigh 0.75 g urea, 0.75 g glucose and 0.45 g manganese sulfate, add urea and manganese sulfate to 30 ml deionized water, stir and dissolve to obtain a precursor solution;
[0045] 2. Transfer the precursor solution to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) to ensure that the reactor is well sealed. Heat the reactor to 200°C and keep it at 200°C for 6 hours. After the reaction is completed, cool it naturally to room temperature, centrifuge the obtained mixed product, dialyze the supernatant with an 8kDa dialysis bag (dialysis fluid is deionized water) for 24 hours, collect the solution in the dialysis bag and freeze-dry it to obtain manganese-doped carbon quantum dots, marked as Mn-CQDs-III;
[0046] 3. Weigh 1g of sodium molybdate and add it to 60mL of deionized water, stir until completely dissolved to obtain a sodium molybdate solution;
[0047] 4. Weigh 0.1 g of manganese-doped carbon quantum dots and 0.05 g of sodium dodecyl sulfate, add manganese-doped carbon quantum dots and sodium dodecyl sulfate to the sodium molybdate solution, respectively, and stir until completely dissolved to obtain a mixed solution;
[0048] 5. Transfer the mixed solution to a reactor with a polytetrafluoroethylene (PTFE) liner, heat the reactor to 220°C, and keep the reaction at 220°C for 12 hours. After the reaction is completed, cool it naturally to room temperature, filter the obtained mixed product, wash the filter cake with deionized water and ethanol alternately for 3 times, and then dry it at 60°C for 8 hours to obtain a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst, marked as Mn-CQDs / MoO3-III.
[0049] Comparative Example 1
[0050] 1. Weigh 0.75 g urea, 0.75 g glucose, and 0.3 g manganese sulfate, add urea, glucose and manganese sulfate into 30 ml deionized water, stir to dissolve, then add 1 g sodium molybdate, continue stirring to dissolve, and obtain a precursor solution.
[0051] 2. Transfer the precursor solution to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) to ensure that the reactor is well sealed. Heat the reactor to 180°C and keep it at 180°C for 12 hours. After the reaction is completed, cool it naturally to room temperature, centrifuge the resulting mixed product, dialyze the supernatant with an 8kDa dialysis bag (dialysis fluid is deionized water) for 24 hours, collect the solution in the dialysis bag and freeze-dry it to obtain manganese and molybdenum dual-doped carbon quantum dots, labeled as Mn / Mo-CQDs.
[0052] The manganese and molybdenum dual-doped carbon quantum dots prepared in this comparative example are spherical, which are single spherical nanoparticles, limiting their photocatalytic performance. In addition, this comparative example adopts a one-step hydrothermal method, in which urea is not only used as a carbon source, but also as a reducing agent, which will convert part of the molybdenum (Mo) in sodium molybdate (Na2MoO4) from +6 valence (Mo 6+ ) is reduced to a lower valence state (such as Mo 5+ 、Mo 4+ ). The presence of multivalent molybdenum may cause disorder in the energy band structure of the material, forming a complex energy level distribution. The disordered energy band structure will inhibit the effective separation of photogenerated electrons and holes, and reduce the photocatalytic activity. The presence of multivalent molybdenum may cause phase change or phase separation in the material, forming an unstable intermediate phase. Phase change or phase separation will reduce the uniformity and stability of the material, affecting its long-term performance.
[0053] Comparative Example 2
[0054] 1. Weigh 0.75 g urea and 0.75 g glucose, add urea and glucose to 30 ml deionized water, stir evenly to obtain a precursor solution;
[0055] 2. Transfer the precursor solution to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) to ensure that the reactor is well sealed. Heat the reactor to 180°C and keep it at 180°C for 12 hours. After the reaction is completed, cool it naturally to room temperature, centrifuge the resulting mixed product, dialyze the supernatant with an 8kDa dialysis bag (dialysis fluid is deionized water) for 24 hours, collect the solution in the dialysis bag and freeze-dry it to obtain carbon quantum dots;
[0056] 3. Weigh 1g of sodium molybdate and add it to 60mL of deionized water, stir until completely dissolved to obtain a sodium molybdate solution;
[0057] 4. Weigh 0.08 g of carbon quantum dots and 0.2 g of sodium dodecyl sulfate, add manganese-doped carbon quantum dots and anionic surfactant to the sodium molybdate solution, respectively, and stir until completely dissolved to obtain a mixed solution;
[0058] 5. Transfer the mixed solution to a reactor with a polytetrafluoroethylene (PTFE) liner, heat the reactor to 200°C, and keep the reaction at 200°C for 18 hours. After the reaction is completed, cool it naturally to room temperature, filter the obtained mixed product, wash the filter cake with deionized water and ethanol alternately for 3 times, and then dry it at 60°C for 8 hours to obtain a carbon quantum dot / molybdenum oxide composite photocatalyst, marked as CQDs / MoO3.
[0059] Experiment 1: Experimental method for the degradation effect of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst on ceftriaxone sodium:
[0060] 1. Weigh 6mg of ceftriaxone sodium and dissolve it in 100mL of deionized water to prepare a ceftriaxone sodium solution. Continuously pass cold water into the jacket of the jacketed beaker to ensure that the jacketed beaker is in the room temperature state. Subsequently, the ceftriaxone sodium solution is added to the jacketed beaker, and 60mg of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst Mn-CQDs / MoO3-I prepared in Example 1 are weighed and added to the jacketed beaker, and adsorbed under dark conditions for 30 minutes by stirring, to reach adsorption equilibrium. Then use a 300W xenon lamp as a light source for illumination for 3h. After the illumination ends, centrifuge for 15min to remove the composite photocatalyst Mn-CQDs / MoO3-I, take the supernatant and measure its absorbance with an ultraviolet spectrophotometer, and calculate the photocatalytic degradation rate of ceftriaxone sodium.
[0061] 2. Treat the Mn-CQDs / MoO3-II prepared in Example 2, the Mn-CQDs / MoO3-III prepared in Example 3, the manganese-doped carbon quantum dots Mn-CQDs-I prepared in Example 1, the manganese-molybdenum dual-doped carbon quantum dots Mn / Mo-CQDs prepared in Comparative Example 1, the carbon quantum dots CQDs prepared in Comparative Example 2, the CQDs / MoO3 prepared in Comparative Example 2, and MoO3 according to the method of step 1.
[0062] Experimental results:
[0063] The degradation effects of different photocatalysts on ceftriaxone sodium Figure 1 As shown by Figure 1It can be seen that under Xe light irradiation, within 3 hours, the degradation rate of ceftriaxone sodium by the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared in Examples 1-3 is as high as over 85%, and the degradation rates of ceftriaxone sodium by the five photocatalysts Mn-CQDs-I, Mn / Mo-CQDs, CQDs / MoO3, CQDs and MoO3 are 30.3%, 39.8%, 51.6%, 21.5% and 12.1%, respectively. The degradation rate of ceftriaxone sodium by the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared by the present invention is significantly higher than that of the five photocatalysts of manganese-doped carbon quantum dots Mn-CQDs-I, manganese and molybdenum dual-doped carbon quantum dots Mn / Mo-CQDs, carbon quantum dots CQDs, CQDs / MoO3 and MoO3. This shows that manganese doping, CQDs and MoO3 have a synergistic effect, which significantly improves the photocatalytic activity of the composite photocatalyst, thereby significantly improving the degradation rate of ceftriaxone sodium.
[0064] Experiment 2: Experimental method for the cyclic degradation effect of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst of the present invention on ceftriaxone sodium:
[0065] 1. Weigh 6 mg of ceftriaxone sodium and dissolve it in 100 mL of deionized water to prepare a ceftriaxone sodium solution. Continuously pass cold water into the jacket of the jacketed beaker to ensure that the jacketed beaker is in room temperature. Then add the ceftriaxone sodium solution to the jacketed beaker, weigh 60 mg of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst Mn-CQDs / MoO3-I prepared in Example 1 and add it to the jacketed beaker, stir and adsorb for 30 minutes under dark conditions to reach adsorption equilibrium. Then use a 300W xenon lamp as a light source for illumination for 3 hours. After the illumination is completed, centrifuge for 15 minutes, take the supernatant and measure its absorbance with an ultraviolet spectrophotometer, and calculate the degradation rate of ceftriaxone sodium. At the same time, the centrifuged precipitate is washed alternately with deionized water and ethanol for 3 times, and then dried at 60 ° C for 3 hours to obtain a recovered manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst.
[0066] 2. The recovered manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst was repeatedly treated according to the method of step 1 for 5 cycles of degradation, and the degradation rate of ceftriaxone sodium was calculated and recorded each time.
[0067] Test results:
[0068] The degradation rate of ceftriaxone sodium by the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared in Example 1 in five consecutive degradation cycles is as follows: Figure 2 As shown by Figure 2 It can be seen that in five consecutive cycles of ceftriaxone sodium degradation, the degradation rate of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst of the present invention was maintained at about 87%, and no deactivation phenomenon was observed, showing good stability and reusability.
Claims
1. A method for preparing a manganese-doped carbon quantum dot / molybdenum oxide composite photocatalyst, characterized in that The steps include: S1. Dissolve urea, glucose and manganese source in deionized water, stir and dissolve to obtain a precursor solution; S2, transferring the precursor solution to a reactor, performing a hydrothermal reaction at 160-200°C for 6-16h, cooling to room temperature after the reaction, centrifuging, dialyzing the supernatant, and drying to obtain manganese-doped carbon quantum dots; S3, dissolving a molybdenum source in deionized water to obtain a molybdenum source solution, adding manganese-doped carbon quantum dots and anionic surfactant to the molybdenum source solution, stirring and dissolving, and obtaining a mixed solution; S4. The mixed solution is transferred to a reactor and subjected to a hydrothermal reaction at 180-220°C for 12-24 hours. After the reaction is completed, the mixed solution is cooled to room temperature, filtered, washed, and dried to obtain a manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst.
2. The method for preparing the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst according to claim 1, characterized in that: The manganese source is selected from manganese sulfate, manganese chloride or manganese acetate.
3. The method for preparing the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst according to claim 1, characterized in that: The mass ratio of the urea, glucose and manganese source is 5:4-6:1-3.
4. The method for preparing the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst according to claim 1, characterized in that: The molybdenum source is selected from sodium molybdate or ammonium molybdate.
5. The method for preparing the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst according to claim 1, characterized in that: The anionic surfactant is selected from sodium dodecyl sulfate or sodium dodecylbenzene sulfonate.
6. The method for preparing the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst according to claim 1, characterized in that: The mass ratio of the manganese-doped carbon quantum dots, the molybdenum source and the anionic surfactant is 1:10-20:1-3.
7. A manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst prepared by any method of claims 1-6.
8. Use of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst according to claim 7 in the degradation of cephalosporin antibiotics.
9. The use of the manganese-doped carbon quantum dots / molybdenum oxide composite photocatalyst in the degradation of cephalosporin antibiotics according to claim 8, characterized in that: The cephalosporin antibiotic is ceftriaxone sodium.