Amorphous molybdenum sulfide / carbon quantum dot composite catalyst, preparation method and application

Abstract

The present application relates to the field of water treatment and specifically discloses an amorphous molybdenum sulfide / carbon quantum dot composite catalyst, a preparation method, and applications. The preparation method comprises the following steps: S1. mixing a carbon quantum dot solution with a hydrochloric acid solution at a volume ratio of (0.5-2.0):30 to obtain a carbon quantum dot hydrochloric acid solution; then mixing the carbon quantum dot hydrochloric acid solution with an ammonium tetrathiomolybdate solution and stirring for 25-35 minutes; S2. washing and filtering the result of step S1, and then vacuum drying at a temperature of 35-45°C for 6-8 hours to obtain an amorphous molybdenum sulfide / carbon quantum dot composite catalyst. Compared to traditional amorphous molybdenum sulfide catalysts, the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared by the preparation method of the present application has stronger catalytic activity against PMS, higher stability in water treatment, and no secondary pollution to water bodies, making it widely applicable to water treatment.

Description

Technical Field

[0001] The present application relates to the field of water treatment, and more specifically, to a method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst and the application of the composite catalyst in water treatment. Background Art

[0002] Pharmaceutical and Personal Care Products (PPCPs) are an emerging class of pollutants, encompassing a wide variety of categories, including various antibiotics, synthetic musks, analgesics, antihypertensive drugs, contraceptives, hypnotics, diet pills, hair sprays, hair dyes, and fungicides. Through human metabolism and daily activities, these highly bioactive, potentially carcinogenic, and poorly biodegradable substances are continuously introduced into natural water bodies, posing a serious threat to the ecological environment and drinking water safety on which humans depend. Although the concentration of PPCPs in aquatic environments is not high, and there are few cases of such substances causing acute toxic effects on humans or animals, PPCPs have a strong ability to accumulate and accumulate in organisms, resulting in potential ecotoxicity. Therefore, the exploration of effective degradation and efficient removal methods for trace PPCPs in water is of great significance for ensuring human drinking water health and protecting the ecological environment.

[0003] Currently, researchers are focusing on methods for controlling PPCPs in water, including adsorption, membrane separation, constructed wetlands, advanced oxidation processes, and combinations of these methods. Advanced oxidation processes, owing to their high degradation efficiency and extensive treatment capabilities, have garnered significant attention in recent years. Among these advanced oxidation processes, sulfate radical-based processes are particularly favored due to their rapid degradation rate, pH adaptability, and high mineralization. The core of sulfate radical-based advanced oxidation processes is the activation of persulfates (peroxymonosulfate (PMS) and peroxydisulfate (PDS)). PMS, due to its highly asymmetric molecule, is more readily activated to produce sulfate radicals than PDS. Since Ball et al. first reported in 1956 that Co could catalyze the generation of strong oxidizing free radicals from oxygen, transition metal / PMS systems have replaced high-energy activation methods such as heat, light, and microwaves as a key research focus for sulfate radical generation. The core problem that has troubled water treatment researchers is that excessive transition metals, while acting as catalysts for PMS to degrade organic matter in water, are also heavy metal pollutants that can cause secondary pollution to the water body. Therefore, the research and development of heterogeneous catalysis based on the transition metal / PMS system - heterogeneous catalysts containing transition metals has gradually become a hot topic in the field of water treatment.

[0004] Molybdenum sulfide compounds are often used to prepare photovoltaic cells, light emitters and other electronic components due to their high electrical conductivity. Molybdenum sulfide compounds are classified according to their structure, including crystalline molybdenum disulfide (MoS2) and amorphous molybdenum sulfide (i.e., amorphous molybdenum sulfide MoS x Crystalline molybdenum disulfide (MoS2) has a layered structure and has high active sites at the edge. In recent years, it has also been used as a catalytic oxidant (PMS) to degrade organic pollutants in water. Amorphous molybdenum sulfide (MoS) has more active sites and more active redox properties. x ) is rarely seen in the field of water treatment. This is because it has active redox properties and also makes MoS x The poor stability in water makes it unsuitable for drinking water treatment. In addition, compared with transition metals such as Co, Fe, and Mn, MoS x The electrons in the catalytic reaction tend to be self-consumed, so the catalytic activity towards PMS is low. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst to obtain a new type of MoS x @CQDs composite catalyst and its application in water treatment.

[0006] In the first aspect, the present application provides a method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst, which adopts the following technical solution:

[0007] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst comprises the following steps:

[0008] S1. A carbon quantum dot solution having a volume ratio of (0.5-2.0): 30 was mixed with a hydrochloric acid solution to obtain a carbon quantum dot hydrochloric acid solution, and then the carbon quantum dot hydrochloric acid solution was mixed with an ammonium tetrathiomolybdate solution and stirred for 25-35 min; wherein the volume ratio of the ammonium tetrathiomolybdate solution to the hydrochloric acid solution was (1.3-1.7): 1;

[0009] S2. The product obtained in step S1 is washed and filtered, and then vacuum-dried at a temperature of 35-45° C. for 6-8 hours to obtain an amorphous molybdenum sulfide / carbon quantum dot composite catalyst.

[0010] By adopting the above technical solution, the present application first mixes the carbon quantum dot solution and the hydrochloric acid solution in a certain volume ratio and stirs them evenly to prepare a carbon quantum dot hydrochloric acid solution, that is, a hydrolyzing agent for the ammonium tetrathiomolybdate solution, and then mixes the hydrolyzing agent with the ammonium tetrathiomolybdate solution in a certain volume ratio and stirs for a certain time, so that the ammonium tetrathiomolybdate can form a coplanar bond with the carbon quantum in the process of hydrolysis to form MoSx, forming a catalyst composite of amorphous molybdenum sulfide and carbon quantum dots, which is better than the traditional amorphous MoS x The amorphous molybdenum sulfide / carbon quantum dot composite catalyst has stronger catalytic activity for PMS, and the doping of carbon quantum dots significantly improves the catalytic activity of amorphous MoS x The stability of the structure greatly enhances its stability in water treatment and can be widely used in water treatment.

[0011] This application optimizes the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution in the carbon quantum dot hydrochloric acid solution, thereby controlling the concentration of the carbon quantum dots in the carbon quantum dot hydrochloric acid solution, and thereby making the prepared amorphous molybdenum sulfide / carbon quantum dot composite catalyst have a stronger catalytic effect on PMS. In one embodiment of the present application, the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution in the carbon quantum dot hydrochloric acid solution is 0.5:30; in one embodiment of the present application, the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution in the carbon quantum dot hydrochloric acid solution is 2:30; and in one embodiment of the present application, the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution in the carbon quantum dot hydrochloric acid solution is 1:30.

[0012] Preferably, in step S1, the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution in the carbon quantum dot hydrochloric acid solution is 1:30.

[0013] By adopting the above technical solution, the present application further optimizes the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution, thereby further improving the catalytic activity of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst on PMS, thereby improving the degradation effect of the system on the PPCPs solution.

[0014] Preferably, the carbon quantum dot solution is prepared by the following method:

[0015] A mixed solution with a solute mass concentration of 0.07-0.09 g / mL was prepared, wherein the solute included citric acid and urea in a weight ratio of (2.5-3.5):1, and then the mixed solution was hydrothermally reacted at a temperature of 160-200° C. for 4.5-5.5 hours, and then cooled to obtain a carbon quantum dot solution.

[0016] By adopting the above technical solution, the present application uses citric acid and urea as carbon source and nitrogen source, and reacts at a certain temperature to form carbon quantum dots. In a specific embodiment of the present application, the solute mass concentration of the mixed solution is 0.07g / mL, and the weight ratio of citric acid and urea is 2.5:1. In a specific embodiment of the present application, the solute mass concentration of the mixed solution is 0.08g / mL, and the weight ratio of citric acid and urea is 3:1. In a specific embodiment of the present application, the solute mass concentration of the mixed solution is 0.09g / mL, and the weight ratio of citric acid and urea is 3.5:1.

[0017] Preferably, the concentration of the hydrochloric acid solution is 0.05-0.15 mol / L. In one embodiment of the present application, the concentration of the hydrochloric acid solution is 0.05 mol / L. In one embodiment of the present application, the concentration of the hydrochloric acid solution is 0.1 mol / L. In one embodiment of the present application, the concentration of the hydrochloric acid solution is 0.15 mol / L.

[0018] Preferably, the concentration of the ammonium tetrathiomolybdate solution is 0.03-0.07 mol / L.

[0019] By adopting the above technical solution, the present application optimizes the concentration of ammonium tetrathiomolybdate solution so that it can form a better coplanar bond with the carbon atom point, thereby improving the catalytic effect of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst. In a specific embodiment of the present application, the concentration of ammonium tetrathiomolybdate solution is 0.03mol / L. In a specific embodiment of the present application, the concentration of ammonium tetrathiomolybdate solution is 0.05mol / L. In a specific embodiment of the present application, the concentration of ammonium tetrathiomolybdate solution is 0.07mol / L.

[0020] In a second aspect, the present application provides a MoSx@CQDs composite catalyst prepared by the above preparation method.

[0021] In a third aspect, the present application provides an application of a MoSx@CQDs composite catalyst in water treatment, using the following technical solution:

[0022] A MoSx@CQDs composite catalyst is used in water treatment. The MoSx@CQDs composite catalyst and PMS are added to a PPCPs solution and stirred at a temperature of 10-45°C for 55-60 minutes.

[0023] Preferably, the concentration of the PPCPs solution is 5-20 μmol / L.

[0024] Preferably, 0.1-0.4 parts by weight of the MoSx@CQDs composite catalyst is added to each liter of the PPCPs solution.

[0025] Preferably, the molar concentration of the PMS in the PCCPs solution is 0.8-1.2 mmol / L.

[0026] By adopting the above technical solution, the present application adds a certain amount of MoSx@CQDs composite catalyst and PMS to a PPCPs solution of a certain concentration, which can stably and efficiently catalyze PMS to degrade PPCPs in water and effectively remove PPCPs pollutants in the solution. In a specific embodiment of the present application, 0.1 parts by weight of MoSx@CQDs composite catalyst is added to each liter of PPCPs solution, and the molar concentration of PMS in the PPCPs solution is 0.8mmol / L. In a specific embodiment of the present application, 0.4 parts by weight of MoSx@CQDs composite catalyst is added to each liter of PPCPs solution, and the molar concentration of PMS in the PPCPs solution is 1.2mmol / L. In a specific embodiment of the present application, 0.2 parts by weight of MoSx@CQDs composite catalyst is added to each liter of PPCPs solution, and the molar concentration of PMS in the PPCPs solution is 1mmol / L.

[0027] In summary, this application has the following beneficial technical effects:

[0028] 1. Compared with traditional amorphous molybdenum sulfide catalysts, the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared by the preparation method of the present application has stronger catalytic activity against PMS, higher stability in water treatment, and does not cause secondary pollution to water bodies, and can be widely used in water treatment;

[0029] 2. The preparation method of the present application has simple steps, is easy to operate, and the raw materials are readily available, the production cost is low, and it is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a scanning electron microscope image of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application;

[0031] Figure 2 This is an energy spectrum scan of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application;

[0032] Figure 3 This is a comparison chart of the degradation effects of coumarin by different systems;

[0033] Figure 4 This is a diagram showing the effect of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application on the degradation of different PPCPs;

[0034] Figure 5This is a diagram showing the cycle effect of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application. DETAILED DESCRIPTION

[0035] The present application is further described in detail below with reference to the accompanying drawings, embodiments and comparative examples.

[0036] The PPCPs solution of this application can contain various antibiotics, synthetic musks, analgesics, antihypertensive drugs, contraceptives, hypnotics, diet pills, hair sprays, hair dyes, and fungicides. This application uses an aqueous solution containing coumarin as an example, with a concentration of 5-20 μmol / L and a pH of 5.8.

[0037] Preparation Example 1

[0038] The preparation method of carbon quantum dot solution is as follows:

[0039] First, 2.5 g of citric acid and 1 g of urea were dissolved in 50 mL of ultrapure water to obtain a mixed solution. The mixed solution was then transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 160° C. for 4.5 h. After natural cooling, a carbon quantum dot solution was obtained.

[0040] Preparation Example 2

[0041] The preparation method of carbon quantum dot solution is as follows:

[0042] First, 3.5 g of citric acid and 1 g of urea were dissolved in 50 mL of ultrapure water to obtain a mixed solution. The mixed solution was then transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 200° C. for 5.5 h. After natural cooling, a carbon quantum dot solution was obtained.

[0043] Preparation Example 3

[0044] The preparation method of carbon quantum dot solution is as follows:

[0045] First, 3 g of citric acid and 1 g of urea were dissolved in 50 mL of ultrapure water to obtain a mixed solution. The mixed solution was then transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 180° C. for 5 h. After natural cooling, a carbon quantum dot solution was obtained.

[0046] Example 1

[0047] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst comprises the following steps:

[0048] S1. 0.5 mL of the carbon quantum dot solution prepared in Preparation Example 1 was added to 30 mL of a 0.05 mol / L hydrochloric acid solution to fully disperse the carbon quantum dot hydrochloric acid solution, and then the carbon quantum dot hydrochloric acid solution was added dropwise to 23 mL of a 0.03 mol / L ammonium tetrathiomolybdate solution at a rate of 1 drop / s under magnetic stirring. After the addition was complete, the mixture was stirred for 25 min;

[0049] S2. The product obtained in step S1 was washed and filtered, and then vacuum-dried at 35° C. for 8 h to obtain an amorphous molybdenum sulfide / carbon quantum dot composite catalyst.

[0050] Example 2

[0051] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst comprises the following steps:

[0052] S1. 0.5 mL of the carbon quantum dot solution prepared in Preparation Example 2 was added to 30 mL of a 0.15 mol / L hydrochloric acid solution to fully disperse the carbon quantum dot hydrochloric acid solution, and then the carbon quantum dot solution was added dropwise to 17 mL of a 0.07 mol / L ammonium tetrathiomolybdate solution at a rate of 1 drop / s under magnetic stirring. After the addition was complete, the mixture was stirred for 35 min;

[0053] S2. The product obtained in step S1 was washed and filtered, and then vacuum-dried at 45° C. for 6 h to obtain an amorphous molybdenum sulfide / carbon quantum dot composite catalyst.

[0054] Example 3

[0055] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst comprises the following steps:

[0056] S1. 0.5 mL of the carbon quantum dot solution prepared in Preparation Example 3 was added to 30 mL of a 0.1 mol / L hydrochloric acid solution to fully disperse the carbon quantum dot hydrochloric acid solution, and then the carbon quantum dot hydrochloric acid solution was added dropwise to 20 mL of a 0.05 mol / L ammonium tetrathiomolybdate solution at a rate of 1 drop / s under magnetic stirring. After the addition was complete, the mixture was stirred for 30 min;

[0057] S2. The product obtained in step S1 was washed and filtered, and then vacuum-dried at 40° C. for 7 h to obtain an amorphous molybdenum sulfide / carbon quantum dot composite catalyst.

[0058] Example 4

[0059] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst is different from that of Example 3 in that: in step S1, the amount of the carbon quantum dot solution used is 2 mL, and the rest is the same as that of Example 3.

[0060] Example 5

[0061] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst is different from that of Example 3 in that: in step S1, the amount of the carbon quantum dot solution used is 1 mL, and the rest is the same as that of Example 3.

[0062] Example 6

[0063] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst is different from that of Example 3 in that: in step S1, the concentration of the ammonium tetrathiomolybdate solution is 0.02 mol / L, and the rest is the same as that of Example 3.

[0064] Example 7

[0065] A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst is different from that of Example 3 in that: in step S1, the concentration of the ammonium tetrathiomolybdate solution is 0.1 mol / L, and the rest is the same as that of Example 3.

[0066] Comparative Example 1

[0067] The difference from Example 3 is that in step S1, the amount of carbon quantum dot solution used is 0.2 mL, and the rest is the same as Example 3.

[0068] Comparative Example 2

[0069] The difference from Example 3 is that in step S0, the amount of carbon quantum dot solution used is 2.5 mL, and the rest is the same as Example 3.

[0070] Comparative Example 3

[0071] The difference from Example 3 is that: in step S1, the volume ratio of ammonium tetrathiomolybdate solution to hydrochloric acid solution is 1:1, wherein the consumption of ammonium tetrathiomolybdate solution is 30 mL, and all the other are the same as in Example 3.

[0072] Comparative Example 4

[0073] The difference from Example 3 is that: in step S1, the volume ratio of ammonium tetrathiomolybdate solution to hydrochloric acid solution is 1:2, wherein the consumption of ammonium tetrathiomolybdate solution is 15mL, and all the other are the same as in Example 3.

[0074] Comparative Example 5

[0075] The difference from Example 3 is that in step S1, the mixing and stirring time after the dropwise addition is 20 minutes, and the rest is the same as Example 3.

[0076] Comparative Example 6

[0077] The difference from Example 3 is that in step S1, the mixing and stirring time after the dropwise addition is 40 minutes, and the rest is the same as Example 3.

[0078] Application Example 1

[0079] An application of a MoSx@CQDs composite catalyst in water treatment comprises the following steps:

[0080] First, 50 mL of a 5 μmol / L coumarin aqueous solution was prepared, and then 5 mg of the MoSx@CQDs composite catalyst prepared in Example 1 was added, and then PMS was added. The molar concentration of PMS in the coumarin aqueous solution was 0.8 mmol / L. The mixture was magnetically stirred at a temperature of 10°C for 60 min.

[0081] Application Example 2

[0082] An application of an amorphous molybdenum sulfide / carbon quantum dot composite catalyst in water treatment comprises the following steps:

[0083] First, 50 mL of a 20 μmol / L coumarin aqueous solution was prepared, and then 20 mg of the MoSx@CQDs composite catalyst prepared in Example 2 was added thereto. Then, PMS was added, and the molar concentration of PMS in the coumarin aqueous solution was 1.2 mmol / L. The mixture was magnetically stirred at 45°C for 55 min.

[0084] Application Example 3

[0085] An application of an amorphous molybdenum sulfide / carbon quantum dot composite catalyst in water treatment comprises the following steps:

[0086] First, 50 mL of a 10 μmol / L coumarin aqueous solution was prepared, and then 10 mg of the MoSx@CQDs composite catalyst prepared in Example 3 was added thereto. Then, PMS was added, and the molar concentration of PMS in the coumarin aqueous solution was 1 mmol / L. The mixture was magnetically stirred at 45°C for 60 min.

[0087] Application Example 4-13

[0088] The application of an amorphous molybdenum sulfide / carbon quantum dot composite catalyst in water treatment is different from Application Example 3 in that the MoSx@CQDs composite catalyst uses the MoSx@CQDs composite catalyst prepared in Examples 4-7 and Comparative Examples 1-6, respectively, and the rest is the same as Application Example 3.

[0089] Comparative Application Example 1

[0090] The difference from Application Example 3 is that: no MoSx@CQDs composite catalyst is added, only PMS is added to the coumarin aqueous solution, and the rest is the same as Application Example 3.

[0091] Comparative Application Example 2

[0092] The difference from Application Example 3 is that PMS is not added, and only the MoSx@CQDs composite catalyst is added to the coumarin aqueous solution. The rest is the same as Application Example 3.

[0093] Comparative Application Example 3

[0094] The difference from Application Example 3 is that an amorphous MoSx catalyst is used instead of the MoSx@CQDs composite catalyst. The rest is the same as Application Example 3. The preparation method of the amorphous MoSx catalyst is as follows: first, 30 mL of a 0.1 mol / L hydrochloric acid solution is added dropwise to 20 mL of a 0.05 mol / L ammonium tetrathiomolybdate solution at a rate of 1 drop / s under magnetic stirring. After the addition is completed, the mixture is mixed and stirred for 30 minutes, and then washed and filtered, and then vacuum dried at 40°C for 7 hours to obtain an amorphous MoSx catalyst.

[0095] Comparative Application Example 4

[0096] The difference from Application Example 3 is that 1 mL of the carbon quantum dot solution prepared in Preparation Example 3 is added to the coumarin aqueous solution instead of the MoSx@CQDs composite catalyst, and the rest is the same as Application Example 3.

[0097] Performance testing

[0098] 1. The amorphous molybdenum sulfide / carbon quantum dot composite catalysts prepared in Examples 1-7 of the present application were subjected to electron microscope scanning and energy spectrum scanning. The results are as follows: Figure 1 and Figure 2 shown.

[0099] from Figure 1 and Figure 2 It can be seen that the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application has a typical flake structure, which is mainly composed of Mo and S elements. As a representative of CQDs, the density of C element is much lower than that of Mo and S elements, and is evenly distributed in the MoS X This indicates that CQDs and MoS X Coplanar bonding allows carbon quantum dots to be successfully loaded without agglomeration.

[0100] 2. The concentration of coumarin in the treated coumarin aqueous solutions in Application Examples 1-13 and Comparative Application Examples 1-4 was detected by liquid chromatography, and the ratio of the coumarin concentration in the coumarin solution after treatment to the coumarin concentration in the coumarin solution before treatment, i.e., C / C0, was calculated. This ratio was used to represent the coumarin degradation effect of different systems. The results are shown in Table 1.

[0101] Table 1 Results of coumarin degradation by different systems

[0102] project <![CDATA[C / C0]]> Application Example 1 0.4325 Application Example 2 0.4416 Application Example 3 0.4222 Application Example 4 0.3547 Application Example 5 0.1065 Application Example 6 0.4308 Application Example 7 0.4269 Application Example 8 0.4743 Application Example 9 0.3729 Application Example 10 0.5327 Application Example 11 0.5514 Application Example 12 0.4316 Application Example 13 0.4219 Comparative Application Example 1 0.8911 Comparative Application Example 2 0.9108 Comparative Application Example 3 0.6235 Comparative Application Example 4 0.9516

[0103] From Table 1 and Figure 3 It can be seen that the C / C0 in Application Examples 1-3 of the present application is between 0.4222-0.4416, which indicates that the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in Examples 1-3 of the present application can effectively catalyze PMS, so that its removal rate of coumarin reaches 56-58%, and has a good degradation effect on PPCPs in the solution.

[0104] The C / C0 in Application Examples 4-5 ranged from 0.1165 to 0.3547, a decrease of 15.99-72.41% compared to Application Example 3. This indicates that the present application significantly improves the coumarin degradation effect by optimizing the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution in the carbon quantum dot hydrochloric acid solution of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst. Specifically, when the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution in the carbon quantum dot hydrochloric acid solution was 1:30, the coumarin removal rate reached 90%, achieving the best coumarin degradation effect.

[0105] The C / C0 in Application Examples 6-7 is slightly higher than that in Application Example 3, which shows that the present application can further improve the catalytic activity of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst for PMS by optimizing the concentration of ammonium tetrathiomolybdate solution in the amorphous molybdenum sulfide / carbon quantum dot composite catalyst, thereby further improving the degradation effect of coumarin.

[0106] The C / C0 in Application Example 8 is 0.4743, which is 12.34% higher than that in Application Example 3. This shows that when the concentration of the carbon quantum dot solution in the carbon quantum dot hydrochloric acid solution is lower than the range of this application, the catalytic activity of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst on PMS will be significantly reduced, thereby reducing the degradation effect of coumarin.

[0107] The C / C0 in Application Example 9 is 0.3729, which is slightly lower than that in Application Example 3, but slightly higher than that in Application Example 4. This shows that when the concentration of the carbon quantum dot solution in the carbon quantum dot hydrochloric acid solution is greater than the range of this application, the degradation effect of coumarin will not continue to increase, but will be slightly reduced.

[0108] The C / C0 in Application Examples 10-11 is higher than that in Application Example 3, which indicates that if the volume ratio of the carbon quantum dot hydrochloric acid catalyst to the ammonium tetrathiomolybdate solution in the amorphous molybdenum sulfide / carbon quantum dot composite catalyst is not within the scope of this application, the catalytic activity of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst for PMS will be reduced, thereby reducing the degradation effect of coumarin.

[0109] The C / C0 in Application Examples 12-13 is higher than that in Application Example 3, which indicates that if the mixing and stirring time of the carbon quantum dot hydrochloric acid catalyst and the ammonium tetrathiomolybdate solution in the amorphous molybdenum sulfide / carbon quantum dot composite catalyst is not within the scope of this application, the catalytic activity of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst for PMS will be reduced, thereby reducing the degradation effect of coumarin.

[0110] The C / C0 in comparative application examples 1-2 is significantly higher than that in application example 3, which indicates that only using amorphous molybdenum sulfide / carbon quantum dot composite catalyst or only using PMS cannot achieve a good degradation effect on coumarin.

[0111] Compared with the C / C0 in Application Example 3 of 0.6235, the removal rate of coumarin was only 38%, which was significantly lower than that in Application Example 3. This shows that the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application has stronger catalytic activity for PMS and higher stability in water treatment than the traditional amorphous molybdenum sulfide catalyst, and can be widely used in water treatment.

[0112] The C / C0 in comparative application example 4 is as high as 0.9516, which is significantly higher than that in application example 3. This shows that the carbon quantum dot catalyst cannot catalyze the degradation effect of PMS on coumarin.

[0113] 3. This application takes Application Example 5 as an example, and performs the same tests and calculations as in Performance Test 2 on other PPCPs in the coumarin solution of Application Example 5. The results are as follows: Figure 4 shown.

[0114] from Figure 4 It can be seen that the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in Preparation Example 5 catalyzes the degradation of coumarin aqueous solution by PMS. In addition to achieving a coumarin removal rate of 90%, the degradation rates of sulfamethoxazole, bisphenol A and carbamazepine by the system also reached 78%, 99% and 66%, respectively. This shows that the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application can effectively catalyze the degradation of various PPCPs by PMS.

[0115] 1. This application takes Application Example 5 as an example to investigate the degradation effect of the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in this application after repeated use. That is, according to the method of Application Example 5, the treatment time is 60 minutes as one cycle, and the treatment effect of each cycle is recorded. The results are shown in Table 2 and Figure 5 shown.

[0116] Table 2 Cycle effect results

[0117] time <![CDATA[Coumarin (C / C0)]]> First cycle (0-60min) 0.10650 Second cycle (60-120 minutes) 0.13141 Third cycle (120-180 minutes) 0.14166 Fourth cycle (180-240 minutes) 0.15098 Fifth cycle (240-300 minutes) 0.16309 Sixth cycle (300-360 minutes) 0.18173

[0118] From Table 2 and Figure 5It can be seen that the amorphous molybdenum sulfide / carbon quantum dot composite catalyst prepared in the present application still has a high degradation effect after repeated recycling. The system can still maintain a removal rate of more than 80% after running at full load for 6 hours, and has high stability.

[0119] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst, characterized in that: The steps include: S1. A carbon quantum dot solution having a volume ratio of (0.5-2.0): 30 was mixed with a hydrochloric acid solution to obtain a carbon quantum dot hydrochloric acid solution, and then the carbon quantum dot hydrochloric acid solution was mixed with an ammonium tetrathiomolybdate solution and stirred for 25-35 min; The volume ratio of ammonium tetrathiomolybdate solution to hydrochloric acid solution is (1.3-1.7):1; S2. The product obtained in step S1 is washed and filtered, and then vacuum-dried at a temperature of 35-45° C. for 6-8 hours to obtain an amorphous molybdenum sulfide / carbon quantum dot composite catalyst.

2. The method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst according to claim 1, wherein In step S1, the volume ratio of the carbon quantum dot solution to the hydrochloric acid solution is 1:

30.

3. The method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst according to claim 1 or 2, wherein: The carbon quantum dot solution is prepared by the following method: A mixed solution with a solute mass concentration of 0.07-0.09 g / mL was prepared, wherein the solute included citric acid and urea in a weight ratio of (2.5-3.5):1, and then the mixed solution was hydrothermally reacted at a temperature of 160-200°C for 4.5-5.5 hours, and then cooled to obtain a carbon quantum dot solution.

4. The method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst according to claim 1, wherein: The concentration of the hydrochloric acid solution is 0.05-0.15 mol / L.

5. The method for preparing an amorphous molybdenum sulfide / carbon quantum dot composite catalyst according to claim 1, wherein: The concentration of the ammonium tetrathiomolybdate solution is 0.03-0.07 mol / L.

6. MoS prepared by the method for preparing the amorphous molybdenum sulfide / carbon quantum dot composite catalyst according to any one of claims 1 to 5 x @CQDs composite catalyst.

7. MoS according to claim 6 x The application of @CQDs composite catalyst in water treatment is characterized by: The MoS x The @CQDs composite catalyst and PMS were added to the PPCPs solution and stirred at a temperature of 10-45°C for 55-60 minutes.

8. A MoS according to claim 7 x The application of @CQDs composite catalyst in water treatment is characterized by: The concentration of the PPCPs solution is 5-20 μmol / L.

9. A MoS according to claim 8 x The application of @CQDs composite catalyst in water treatment is characterized by: 0.1-0.4 g of MoS was added per liter of the PPCPs solution. x @CQDs composite catalyst.

10. A MoS according to claim 8 x The application of @CQDs composite catalyst in water treatment is characterized by: The molar concentration of the PMS in the PPCPs solution is 0.8-1.2 mmol / L.

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