Method for catalytic degradation of organic dyes by using Cu modified C nanospheres

Abstract

The application discloses a method for catalytic degradation of synergistic organic dyes by Cu-modified C nanospheres, and synthesis of the Cu-modified C nanospheres mainly comprises the following steps: C nanospheres are successfully prepared by using the decomposition characteristics of ascorbic acid under acidic and high-temperature conditions; and CuCl2 is in-situ reduced by using an ethanol solution of NaBH4 as a strong reducing agent, and the CuCl2 is modified on the surface of the C nanospheres. Researches show that the Cu interface-modified C nanocrystals (C@Cu) can be used for catalytic degradation of synergistic dyes and p-nitrophenol. The synergistic effect of the C nanospheres and the Cu nanocrystals can optimize the adsorption and desorption balance of the catalytic interface, and accelerate the reaction progress. Compared with the elemental C nanospheres and the Cu nanocrystals, the C@Cu provided by the application has more excellent catalytic performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanomaterial preparation and organic catalysis, and particularly relates to a method for catalytic degradation of organic dyes by using Cu modified C nanospheres. BACKGROUND

[0002] As an important synthetic dye, azo dyes bring us beauty and fashion, but also cause a series of safety and environmental problems. For example, most dyes can reduce the penetration of sunlight through water bodies, thereby inhibiting the photosynthesis of aquatic plants and animals, and posing a potential threat to the survival and reproduction of aquatic organisms. In addition, azo dyes also have the characteristics of chronic toxicity, carcinogenicity and neurotoxicity, which are harmful to human health. For example, long-term exposure to methylene blue (MB) may cause mental illness, nausea, eye irritation, excessive sweating and respiratory problems.

[0003] 4-nitrophenol, also known as 4-nitrophenol (4-NP), is an important organic compound in the field of chemistry. Compared with 4-NP, 4-aminophenol (4-AP) has low hazard and easy biodegradability, and is widely used in the manufacturing process of analgesic and antipyretic drugs. Studies have shown that under the participation of a catalyst, a strong reducing agent (NaBH4) can effectively catalyze the conversion of 4-NP to 4-AP. However, due to its excellent thermal stability, 4-NP can exist in the natural environment for a long time. Without the action of a catalyst, the kinetics of dye and 4-NP reduction is extremely slow. With the spontaneous decomposition of NaBH4 at room temperature, the reduction reaction will also be terminated soon. Based on the above analysis, developing an efficient catalyst to convert dyes such as MB and 4-NP into low-toxicity or easily degradable substances is the key to promoting the development of environmental protection.

[0004] Metallic Cu is one of the earliest metals used by humans. Compared with other noble metal materials, it has stronger adsorption capacity for 4-NP and more excellent catalytic activity. In 2014, the applicant's group prepared an antioxidant Cu elemental nanocrystal and used it to catalyze the reduction of 4-NP (CN104014816A). However, there are still some problems in using Cu elemental nanocrystals to catalyze 4-NP and degrade dyes.

[0005] 1) Small size Cu nanocrystals without surfactants have high surface energy, poor dispersibility, and are easy to agglomerate, resulting in reduced efficiency of the catalyst.

[0006] 2) The use of surfactants can improve the dispersibility of small size Cu nanocrystals, but the number of active sites is reduced and exposed during catalysis due to the coverage of the Cu surface by the active agent ligand, greatly reducing the catalytic efficiency.

[0007] Carbon (carbon nanotubes, graphene) can be used as a carrier of nanomaterials to form stable interaction with nanomaterials, thereby preventing the agglomeration between nanoparticles and improving the monodispersity of nanomaterials. However, the preparation process of traditional carbon support materials is harsh (it is necessary to accurately control the composite conditions such as temperature, pressure, solvent, etc.), and there are greater safety hazards in large-scale production. In order to realize the uniform dispersion of nanomaterials on carbon, the preparation process is often more complex. Since most of the C single element has limited activity in catalytic dye degradation, reasonable control of the production cost is the key to improving the practicability and economy of C supported catalytic materials. SUMMARY

[0008] The present application solves the technical problems of Cu nanomaterials mentioned in the background art, and provides a preparation method of C nanospheres modified by Cu (C@Cu) and its application in synergistic catalytic degradation of 4-NP and dyes. The selected C nanospheres have high dispersibility, and can effectively avoid the aggregation of small-size Cu nanocrystals as a carrier. Since no surfactant is used in the preparation process, the present application can maximize the number of Cu surface catalytic active sites while avoiding the aggregation of Cu nanocrystals.

[0009] The obtained C@Cu has better catalytic activity than traditional Cu nanocrystals and good durability.

[0010] The preparation method of the provided C@Cu is simple, and the specific preparation process is as follows:

[0011] 1) Dilute the concentration of dilute hydrochloric acid to 0.5-0.6 mol / L with deionized water, stir and mix uniformly to obtain a mixed solution 1;

[0012] 2) Weigh ascorbic acid according to the proportion, add it to the mixed solution 1, stir uniformly at room temperature, and after the ascorbic acid is completely dissolved, obtain a mixed solution 2;

[0013] 3) Pour the mixed solution 2 into the reaction kettle, heat to 120℃ and react for 1 hour;

[0014] 4) Select ethanol solution, KOH powder as solute, mix according to the proportion, stir uniformly to make the KOH powder completely dissolved, and mark it as solution 3;

[0015] 5) After the reaction kettle is heated, cool it to room temperature naturally, pour the reaction product of the heated mixed solution 2 into the solution 3, and ultrasonic disperse for 30 minutes to obtain a mixed solution 4;

[0016] 6) Prepare a NaBH4 solution with deionized water as the solvent, add it to the mixed solution 4 according to the proportion to obtain a mixed solution 5;

[0017] 7) Deionized water as solvent, configuration CuCl2 aqueous solution, after stirring uniform 8 times dropwise into the solution 5, every 1 minute, get mixed solution 6;

[0018] 8) Continue to ultrasonic reaction of mixed solution 6 at 40 DEG C for 20 minutes;

[0019] 9) After ultrasonic mixed solution 6 is centrifuged, the powder is extracted with deionized water and ethanol to wash the precipitate 1-3 times, then centrifuged, 40-50 DEG C drying 12 hours, the powder obtained is C@Cu.

[0020] In the application, we use the decomposition characteristics of ascorbic acid under acidic and high temperature conditions to successfully prepare C nanospheres. At the same time, we use NaBH4 ethanol solution as a strong reducing agent to reduce CuCl2 in situ and modify it on the surface of C nanospheres. In order to ensure the efficient decomposition of ascorbic acid, we introduce hydrochloric acid solution in step 1) to reduce the pH value of the solution. In step 4), we use KOH to neutralize the hydrochloric acid solution in step 1), thereby reducing the formation of Cu oxides in the interface modification process.

[0021] Correspondingly, the application also discloses a C@Cu obtained by the preparation method of the C@Cu.

[0022] In addition, the application also discloses a method for catalyzing 4-NP solution and degrading Rhodamine B (Rhb), MB and other dyes by using C@Cu, and the specific method is as follows:

[0023] 1) Take 0.1 mmol / L 4-NP into a cuvette and place it in an ultraviolet-visible spectrometer to test the initial solution, and then take out the cuvette after testing.

[0024] 2) The C@Cu catalyst is configured into a 15 mmol / L suspension, 0.2 mL of the suspension is dropped into the cuvette containing 4-NP in step 1, and ultrasonic is uniform, to achieve adsorption equilibrium, to obtain mixed solution 1.

[0025] 3) The volume of mixed solution 1 in the cuvette is reduced by half, 0.7 mL of 40 mmol / L NaBH4 solution is quickly added, the spectrum parameters are set, and the ultraviolet-visible absorption spectrum is continuously measured until 4-NP is completely degraded (the same time interval is collected each time).

[0026] The dye catalytic degradation process is the same as the catalytic 4-NP reduction step (see application examples 2-3 for details).

[0027] The application has the following beneficial effects:

[0028] 1. The C@Cu has high yield, low cost and is easy to industrialize.

[0029] The present application provides Cu interface modification C nanospheres (C@Cu) and is used for synergistic dye and catalytic degradation of 4-NP. In the preparation process of C@Cu, the C source of C elemental nanospheres is provided by ascorbic acid (also known as vitamin C). The raw materials have little harm to the environment, which reduces the environmental impact and health hazards of researchers in the catalyst preparation process.

[0030] By adjusting the pH value of the reaction solution, the yield of C nanospheres is improved. Only one step is needed to achieve the whole process, which successfully solves the problem of low yield of existing C support material.

[0031] Compared with pure elemental Cu synthesis, the preparation cost of C@Cu is greatly reduced. The preparation steps are simple and can be mass-produced. The technical problem of complex preparation process of existing C carbon elemental support material (carbon nanotube, graphene) is solved.

[0032] 2. Improve Cu dispersion while ensuring high catalytic activity.

[0033] The present application utilizes metal Cu interface modification C nanospheres. C nanospheres as support material can effectively prevent the aggregation of Cu elemental particles, and Cu nanocrystals are uniformly dispersed on the surface of C nanospheres through in-situ deposition. When used for catalyzing 4-NP reduction, the catalytic activity of the obtained C@Cu is higher than that of pure Cu and pure C nanospheres. It has a synergistic catalytic effect. In the process of catalyzing 4-NP reduction at room temperature, the catalytic activity of C@Cu is 1.93 times that of pure Cu. It successfully solves the problem of low catalytic activity of existing Cu nanocrystals.

[0034] 3. Make full use of the synergistic effect of C nanospheres and metal Cu to realize the adsorption and desorption balance of the catalytic interface.

[0035] The present application makes full use of the synergistic effect of C nanospheres and Cu nanocrystals. Compared with Cu elemental, C nanospheres have low catalytic activity, but have strong adsorption strength to 4-NP molecules on the interface, and the adsorption strength is higher than that of Cu nanocrystals. The strong adsorption of C nanospheres to the molecules on the catalytic interface can achieve the purpose of optimizing the adsorption and desorption balance of the catalytic interface, which helps to speed up the reduction reaction of 4-NP solution and realizes the synergistic effect of catalyzing 4-NP reduction. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The X-ray diffraction pattern of the sample obtained in Example 1 of the present application.

[0037] Figure 2 The field emission scanning electron microscope picture of the C nanospheres obtained in Comparative Example 1 of the present application.

[0038] Figure 3 It is the real photo after the reaction of Comparative Example 2 of the present application.

[0039] Figure 4 is the X-ray diffraction pattern of the sample obtained in Inventive Example 1.

[0040] Figure 5 is the real-time spectrum of the catalytic reduction of 4-NP at 20 degrees Celsius of the sample obtained in Inventive Example 1 (Application Example 1).

[0041] Figure 6 is the linear fitting function of ln(C / C0) and reaction time when the sample obtained in Inventive Example 1 catalyzes the reduction of 4-NP.

[0042] Figure 7 is the durability test of the catalytic reduction of 4-NP of the sample obtained in Inventive Example 1.

[0043] Figure 8 is the linear fitting function of ln(C / C0) and reaction time when the sample obtained in Inventive Example 1 catalyzes the reduction of 4-NP at different temperatures.

[0044] Figure 9 is the reaction fitting function of ln k and 1000 / T when the sample obtained in Inventive Example 1 catalyzes the reduction of 4-NP (k is the reaction rate).

[0045] Figure 10 is the linear fitting function of ln(C / C0) and reaction time when the sample obtained in Inventive Example 1 catalyzes the reduction of 4-NP at 20 degrees Celsius.

[0046] Figure 11 is the linear fitting function of ln(C / C0) and reaction time when the sample obtained in Inventive Example 1 catalyzes the reduction of 4-NP at 20 degrees Celsius.

[0047] Figure 12 is the real-time absorption spectrum of the catalytic degradation of dye MB of the sample obtained in Inventive Example 1 (Application Example 2).

[0048] Figure 13 is the real-time absorption spectrum of the catalytic degradation of dye MB of the sample obtained in Inventive Example 1.

[0049] Figure 14 is the real-time absorption spectrum of the catalytic degradation of dye MB of the sample obtained in Inventive Example 1.

[0050] Figure 15 is the real-time absorption spectrum of the catalytic degradation of Rhb dye of the sample obtained in Inventive Example 1 (Application Example 3).

[0051] Figure 16 is the real-time absorption spectrum of the catalytic degradation of Rhb dye of the sample obtained in Inventive Example 1.

[0052] Figure 17 is the real-time absorption spectrum of the sample obtained in Example 3 catalyzing the degradation of dye Rhb. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be described in further detail below with reference to the drawings.

[0054] Example 1: Preparation of C@Cu nanocrystals

[0055] 1) 10 mL of 3 mol / L dilute hydrochloric acid was dissolved in 43 mL of deionized water, stirred and mixed uniformly to obtain mixed solution 1;

[0056] 2) 2.3 g of ascorbic acid was weighed and added to mixed solution 1, stirred at room temperature, and after the ascorbic acid was completely dissolved, mixed solution 2 was obtained;

[0057] 3) Mixed solution 2 was poured into a reaction kettle, heated to 120°C, and heated for 1 hour;

[0058] 4) 3.36 g of KOH powder was weighed and added to 120 mL of ethanol solution, denoted as solution 3, and stirred for 10 minutes to completely dissolve the KOH powder;

[0059] 5) After the oven was heated and cooled, mixed solution 2 was poured into solution 3, and mixed solution 4 was obtained after ultrasonic treatment for 30 minutes;

[0060] 6) 3.0 g of NaBH4 was weighed and dissolved in 40 mL of deionized water, and added to mixed solution 4 to obtain mixed solution 5;

[0061] 7) 388 mg of CuCl2·2H2O was dissolved in 8 mL of deionized water, stirred uniformly, and added dropwise to mixed solution 5 in 8 portions, with a 1-minute interval between each drop, and 1 mL was added each time, to obtain mixed solution 6;

[0062] 8) Mixed solution 6 was continuously ultrasonically treated at 40°C for 20 minutes;

[0063] 9) The ultrasonically treated mixed solution 6 was centrifuged, and the precipitate was washed with deionized water and ethanol 1-3 times, respectively, and then centrifuged again, and the powder obtained by drying in a blast drying oven at 45°C for 12 hours was C@Cu.

[0064] In order to explore the composition of the product, the obtained product was subjected to X-ray diffraction test, and the results are as follows Figure 1As shown in the figure, the X-ray diffraction pattern of the obtained sample corresponds to the peaks on the JCPDS standard diffraction card for Cu (89-2838). In addition, a small amount of impurity peaks appear in the product, corresponding to the peaks on the JCPDS standard diffraction card for Cu2O (1-1142). Apart from these, there are no other characteristic peaks of oxides. The formation of a small amount of Cu2O is due to incomplete liquid-phase reduction. Considering that the product provided by this invention is mainly used in the fields of catalysis and dye degradation, Cu2O itself also possesses this catalytic performance. Therefore, the presence of a small amount of Cu2O will not affect the catalytic and dye degradation performance of the product. Combined with the energy dispersive spectroscopy test in Comparative Example 1, the product also contains amorphous elemental C (no X-ray diffraction peaks). Therefore, it is proven that the obtained product is a C@Cu composite nanomaterial.

[0065] In Example 1 of this invention, steps 1-3) are mainly used for the preparation of C nanospheres, steps 4-8 are mainly used for modifying elemental Cu at the interface of C nanospheres, and step 9) is used for product extraction.

[0066] To investigate the morphology and composition of the obtained elemental C, we performed the operation of Comparative Example 1. The specific steps are as follows.

[0067] Comparative Example 1: Preparation of C nanospheres

[0068] 1) Dissolve 10 mL of 3 mol / L dilute hydrochloric acid in 43 mL of deionized water, stir and mix thoroughly to obtain mixed solution 1;

[0069] 2) Weigh 2.3g of ascorbic acid and add it to mixed solution 1. Stir at room temperature until the ascorbic acid is completely dissolved to obtain mixed solution 2.

[0070] 3) Pour mixed solution 2 into the reaction vessel, heat to 120℃, and heat for 1 hour;

[0071] 4) After the reaction vessel is heated and cooled, the reaction solution is taken out and centrifuged. It is washed with deionized water and ethanol 1 to 3 times. After centrifugation, it is dried in a 45°C forced-air drying oven for 12 hours. The resulting black powder is the product.

[0072] To investigate the composition of the sample obtained in Comparative Example 1, we performed energy-dispersive X-ray spectroscopy (EDS) on the sample. The carbon atom percentage was found to be over 78.45%. Furthermore, the X-ray diffraction pattern showed that the sample obtained in the comparative example was amorphous elemental carbon.

[0073] To demonstrate the microstructure of the sample obtained in Comparative Example 1, we performed scanning electron microscopy (SEM) tests on it, and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the obtained C nanoparticles are regularly arranged spheres with a diameter of 1-2 micrometers.

[0074] In the preparation of C@Cu (Example 1), the step 1) in the present application is the key to obtain C elemental nanospheres. In order to verify this key parameter, we perform Comparative Example 2 operation, the specific steps are as follows.

[0075] Comparative Example 2: Key parameters (influence of reaction liquid pH value on C nanosphere generation)

[0076] 1) Weigh 2.3g ascorbic acid into 53mL deionized water, stir for 5 minutes, and after the ascorbic acid is completely dissolved, obtain a mixed solution 2, pour into the reaction kettle;

[0077] 2) Pour the mixed solution 2 into the reaction kettle, heat to 120℃, and heat for 1 hour;

[0078] Compared with Example 1, Comparative Example 1 replaces "hydrochloric acid" with an equal amount of deionized water. As shown in Figure 3 It can be seen that after heating is completed, there is no precipitation in the solution of Comparative Example 1, and C nanospheres cannot be obtained.

[0079] In summary, adding an appropriate concentration of hydrochloric acid is one of the key parameters in the preparation process of C nanoparticles in the present application. In an acidic environment, ascorbic acid can be more easily decomposed at high temperature, thereby generating C nanospheres.

[0080] In the present application, metal Cu is modified on the surface of C nanospheres by in-situ deposition method to obtain C@Cu product. C nanospheres act as supporting materials to prevent Cu particles from aggregating. NaBH4 used in step 6 of Example 1 is used as a strong reducing agent to reduce CuCl2·2H2O used in step 7 to metal Cu. The KOH powder used in step 4 is used to increase the reducing property of NaBH4. In order to prove that the deposition of the obtained metal Cu on C is irrelevant to steps 1-4, Comparative Example 3 is used as an example to illustrate.

[0081] Comparative Example 3: Preparation of Cu nanocrystals (without C nanosphere support)

[0082] 1) Weigh 3.36g of KOH powder into 120mL of ethanol solution, mark as solution 1, and stir until the KOH powder is completely dissolved;

[0083] 2) Weigh 3.0g of NaBH4 and dissolve in 40mL of deionized water, add to the mixed solution 1, and obtain a mixed solution 2;

[0084] 3) Weigh 388mg of CuCl2·2H2O and dissolve in 8mL of deionized water, and after stirring uniformly, add to the mixed solution 2 in 8 times, with an interval of 1 minute each time, to obtain a mixed solution 3;

[0085] 4) Mix solution 3 continues to be ultrasonic at 40℃ for 20 minutes;

[0086] 5) After ultrasonic, centrifugal separation is carried out to the mixed solution 6, the precipitate is washed 1-3 times with deionized water and ethanol, and then centrifugal separation is carried out again, and after centrifugal separation, drying is carried out in a 45℃ air-drying oven for 12 hours.

[0087] In order to explore the composition of the obtained product, the obtained sample is tested for X-ray diffraction, and the results are shown in Figure 4 As can be seen from the figure, the X-ray diffraction pattern of the obtained sample corresponds to the Cu standard diffraction JCPDS card (89-2838). At the same time, it also corresponds to the Cu2O standard diffraction JCPDS card (1-1142), and in addition, it does not contain other oxide characteristic peaks, thereby proving that the deposition of Cu on the C nanospheres in steps 1-4) is irrelevant to the described preparation mechanism, which is consistent with the conclusion of the described preparation mechanism.

[0088] The C@Cu obtained by the application can be used for catalyzing the reduction of 4-NP, and the specific implementation method is as follows:

[0089] Application Example 1: C@Cu catalyzes the reduction of p-nitrophenol

[0090] 1) 3.4mL of 4-NP solution with a concentration of 0.1mmol / L is placed in a cuvette under the condition of 20℃, the parameters are set, the ultraviolet-visible absorption spectrum of the initial solution is measured, and the cuvette is taken out after the test is completed;

[0091] 2) The C@Cu sample obtained in Example 1 is configured into a suspension with a concentration of 15mmol / L, and after ultrasonic is uniform, 0.2mL of the suspension is taken and dropped into the cuvette containing 3.4mL of 4-NP solution (0.1mmol / L) using a dropper, and then ultrasonic is uniform again, and the adsorption equilibrium is obtained, and the mixed solution 1 is obtained.

[0092] 3) The volume of the mixed solution 1 in the cuvette is halved to 1.8mL, and then it is poured into the cuvette again, and 0.7mL of NaBH4 (40mmol / L) solution is quickly added, and the spectrum is continuously measured until 4-NP is completely degraded, and the single collection time interval is 17s.

[0093] In this application example 1, the spectrum measured in step 1) is the standard 4-NP absorption spectrum; the spectrum measured in step 2) is the absorption spectrum of the sample after reaching the adsorption equilibrium with 4-NP; and the spectrum obtained in step 3) is the real-time spectrum of the process of reducing 4-NP to 4-AP under the action of NaBH4.

[0094] As Figure 5The absorption peak at 310 nm corresponds to the 4-NP solution. After the addition of NaBH4, the absorption peak shifts to 400 nm, which is due to the increase of the basicity of the solution. There is no characteristic peak of C@Cu in the solution, but it accelerates the reduction process and catalyzes the reduction of 4-NP. After 102 s of reaction time, the absorption peak at 400 nm gradually decreases and finally disappears. At the same time, a new peak appears at 298 nm (corresponding to the reduced product 4-AP), and the intensity increases continuously.

[0095] During the reduction process, the catalyst decomposes NaBH4 to produce BH4 - , and 4-NP is adsorbed on the surface of the carrier together with BH4 - . C@Cu reacts with BH4 - to transfer hydrogen atoms and electrons to attack the nitro (-NO2) group on 4-NP, reducing it to an amino (-NH2) group to form 4-AP molecules and then desorbing into the solution. To quantitatively evaluate the catalytic performance of the obtained C@Cu, we calculated the reaction rate (k). As Figure 6 shown, according to the function relationship diagram of ln(C / C0) and reaction time, we can calculate the reaction rate constant of C@Cu catalysis at 20°C as 0.029 / s -1 .

[0096] To verify the durability of the obtained C@Cu in the application of catalyzing 4-NP reduction, we recycled the obtained C@Cu. The reaction time interval for each measurement was 107 s. As Figure 7 , in the first round of catalysis, the reduction rate of 4-NP was 95.1%. In the second round of catalysis, the reduction rate of 4-NP was 80.6%. The reduction rate of 4-NP decreased for two reasons: on the one hand, the loss of catalyst during the recycling process; on the other hand, the coverage of the active sites of C@Cu by 4-AP molecules. However, compared with the first catalysis, the reduction efficiency of the second catalysis did not decrease significantly, indicating that C@Cu as a catalyst in the reduction of 4-NP has good stability.

[0097] To explore the activation energy of C@Cu in the catalytic process, we tested the reaction rate of 4-NP reduction catalyzed by C@Cu at 30°C and 40°C, respectively. As Figure 8 , the linear function fitting diagram of In(C / C0) of the catalytic 4-NP reaction solution with time at 293K (20°C), 303K (30°C) and 313K (40°C) reaction temperatures, respectively. With the increase of reaction temperature, the reaction rate (k) value increases. According to the Arrhenius equation, the activation energy of C@Cu is 16.96 kJ / mol (as Figure 9), which is much higher than the same kind of catalyst. It is proved that C@Cu can reduce the activation energy of the reaction, accelerate the reduction of 4-NP, and has high catalytic activity.

[0098] Compared with elemental C nanospheres and Cu nanocrystals, the Cu-modified C nanospheres (C@Cu) of the application have excellent catalytic performance. In order to verify this, the C nanospheres obtained in Comparative Example 1 and the product obtained in Comparative Example 3 were used as catalysts to catalyze the reduction of 4-NP, and the specific operation was as follows:

[0099] Comparative Example 4: C nanospheres (sample obtained in Comparative Example 1) catalyze the reduction of p-nitrophenol

[0100] 1) Under the environment of 20 degrees Celsius, 3.4 mL of 4-NP solution with a concentration of 0.1 mmol / L was taken into a cuvette, the parameters were set, the ultraviolet-visible absorption spectrum of the initial solution was measured, and the cuvette was taken out after the test was completed;

[0101] 2) The sample obtained in Example 1 (C nanospheres) was configured into a suspension with a concentration of 15 mmol / L, and after ultrasonic homogenization, 0.2 mL of the suspension was taken and dropped into the cuvette containing 3.4 mL of 4-NP solution (0.1 mmol / L), and then ultrasonic homogenization was performed again to obtain a mixed solution 1

[0102] 3) The volume of the mixed solution 1 in the cuvette was halved (to 1.8 mL), and then it was poured into the cuvette again, and 0.7 mL of NaBH4 solution with a concentration of 40 mmol / L was quickly added, and the spectrum was continuously measured until 4-NP was completely degraded, and the single collection time interval was 17 s.

[0103] According to the first-order reaction kinetics, Figure 10 a linear function relationship between ln(C / C0) and reaction time was shown. From Figure 10 it can be seen that the reaction rate of C approaches 0 in the process of catalyzing 4-NP, and it is almost impossible to catalyze the reduction of 4-NP.

[0104] Comparative Example 5: Cu nanocrystals (sample obtained in Comparative Example 3) catalyze the reduction of p-nitrophenol

[0105] 1) Under the environment of 20 degrees Celsius, 3.4 mL of 4-NP solution with a concentration of 0.1 mmol / L was taken into a cuvette, and the ultraviolet-visible absorption spectrum (spectrum range: 290-500 nm) of the initial solution was measured. After the test was completed, the cuvette was taken out;

[0106] 2) Prepare a suspension of the sample (Cu nanocrystals) obtained in Example 3 with a concentration of 15 mmol / L. After sonication, take 0.2 mL of the suspension and add it dropwise into a cuvette containing 3.4 mL of 4-NP solution (0.1 mmol / L). Sonicate again until adsorption equilibrium is reached to obtain mixture 1.

[0107] 3) Reduce the volume of mixture 1 in the cuvette by half to 1.8 mL, pour it back into the cuvette, and quickly add 0.7 mL of NaBH4 solution with a concentration of 40 mmol / L. Continuously measure the spectrum until 4-NP is completely degraded, with a single acquisition time interval of 17 s.

[0108] like Figure 11 As shown, the reaction rate of 4-NP under the catalysis of the sample (Cu nanocrystals) obtained in Example 3 is 0.0153 / s. -1 In comparison, the reaction rate of C@Cu obtained in Example 1 of this patent during the catalytic process is 0.0290 / s. -1 The catalytic activity was approximately doubled compared to the sample obtained in Example 3.

[0109] The enhanced catalytic efficiency of C@Cu is due to two reasons: 1) C nanospheres, as a supporting material, facilitate the dispersion of Cu nanocrystals and increase the specific surface area; 2) C itself has a strong adsorption capacity, which accelerates the reaction kinetics during catalysis and helps to achieve the adsorption-desorption equilibrium of reactants at the interface, thereby accelerating the process of 4-NP to 4-AP conversion.

[0110] In addition to catalyzing the reduction of 4-NP, numerous experiments have shown that the C@Cu obtained in this invention has excellent catalytic performance for the degradation of dyes such as MB (methylene blue), Rhb (rhodamine B), MO (methyl orange), and Congo Red. Due to the large amount of design data, this patent only describes in detail the specific results for the more difficult-to-degrade MB (application example 2) and Rhb (application example 3).

[0111] Application Example 2: C@Cu Catalyzed Degradation of MB

[0112] 1) At room temperature, prepare a 0.1 mmol / L MB solution, take 3.4 mL and put it into a cuvette, measure the absorption spectrum of the initial solution (spectral range 500-750 nm), and remove the cuvette after the test is completed;

[0113] 2) Prepare a suspension of C@Cu sample obtained in Example 1 with a concentration of 15 mmol / L. After sonication, take 0.2 mL of the suspension and drop it into a cuvette containing 3.4 mL of MB solution (0.1 mmol / L) using a dropper. Sonicate again until adsorption equilibrium is reached to obtain mixture 1.

[0114] 3) The volume of mixed solution 1 in the cuvette is halved to 1.8 mL, and then poured into the cuvette again. A 0.7 mL NaBH4 solution with a concentration of 40 mmol / L is quickly added. The spectrum is continuously measured until the MB is completely degraded. The single collection time interval is 21 s.

[0115] As shown in Figure 12 , the characteristic peak of MB is located at 675 nm. After the addition of the catalyst, the characteristic peak disappears at 108 s, indicating that it is completely degraded. In order to verify the excellent application performance of the product of the application in the catalytic degradation of dyes, Comparative Example 3 and Comparative Example 4 are carried out. The specific operation steps are as follows:

[0116] Comparative Example 6: C nanospheres (sample obtained in Comparative Example 1) catalyze the degradation of MB

[0117] 1) At room temperature, a 0.1 mmol / L MB solution is prepared, and 3.4 mL is taken into a cuvette. The ultraviolet-visible absorption spectrum of the initial solution (spectrum range: 500-750 nm) is measured. After the test is completed, the cuvette is taken out;

[0118] 2) A 15 mmol / L suspension of C elemental nanospheres obtained in Comparative Example 1 is prepared. After ultrasonic homogenization, 0.2 mL of the suspension is taken and dropped into the cuvette containing 3.4 mL of the MB solution (0.1 mmol / L) using a dropper. After ultrasonic homogenization again, the adsorption equilibrium is achieved, and mixed solution 1 is obtained;

[0119] 3) The volume of mixed solution 1 in the cuvette is halved to 1.8 mL, and then poured into the cuvette again. A 0.7 mL NaBH4 solution with a concentration of 40 mmol / L is quickly added. The spectrum is continuously measured until the MB is completely degraded. The single collection time interval is 20 s.

[0120] As shown in Figure 13 , after a reaction time of 160 s, the characteristic peak at 675 nm does not decrease, proving that MB is not degraded. The catalytic performance of the C nanospheres obtained in Comparative Example 1 for the degradation of dye MB is almost zero.

[0121] Comparative Example 7: Cu nanocrystals (sample obtained in Comparative Example 3) catalyze the degradation of MB

[0122] 1) At room temperature, a 0.1 mmol / L MB solution is prepared, and 3.4 mL is taken into a cuvette. The ultraviolet-visible absorption spectrum of the initial solution (spectrum range: 500-750 nm) is measured. After the test is completed, the cuvette is taken out;

[0123] 2) The elemental Cu obtained in Comparative Example 3 was configured into a suspension with a concentration of 15 mmol / L, and after being uniformly ultrasonicated, 0.2 mL of the suspension was taken and dropped into a cuvette containing 3.4 mL of the MB solution (0.1 mmol / L) using a dropper, and then uniformly ultrasonicated again to reach adsorption equilibrium, to obtain mixed solution 1;

[0124] 3) The volume of mixed solution 1 in the cuvette was halved (to 1.8 mL), and then poured into a cuvette again, and 0.7 mL of the NaBH4 solution with a concentration of 40 mmol / L was quickly added, and the spectrum was continuously measured until the MB was completely degraded, and the single collection time interval was 24 s.

[0125] As shown in FIG. 2, the characteristic peak of MB is located at 664 nm, and after the catalyst obtained in Comparative Example 3 was used for catalysis, the characteristic peak disappeared after 168 s, indicating that the MB was completely degraded. Figure 14

[0126] Application Example 3: C@Cu catalyzing the degradation of Rhb

[0127] 1) At room temperature, a Rhb solution with a concentration of 0.1 mmol / L was configured, 3.4 mL of which was taken and put into a cuvette, and the absorption spectrum of the initial solution (the spectrum range was 400-650 nm) was measured, and then the cuvette was taken out after the test was completed;

[0128] 2) The C@Cu sample obtained in Example 1 was configured into a suspension with a concentration of 7.5 mmol / L, and after being uniformly ultrasonicated, 0.2 mL of the suspension was taken and dropped into a cuvette containing 3.4 mL of the Rhb solution (0.1 mmol / L) using a dropper, and then uniformly ultrasonicated again to reach adsorption equilibrium, to obtain mixed solution 1;

[0129] 3) The volume of mixed solution 1 in the cuvette was halved (to 1.8 mL), and then poured into a cuvette again, and 0.7 mL of the NaBH4 solution with a concentration of 40 mmol / L was quickly added, and the spectrum was continuously measured until the Rhb was completely degraded, and the single collection time interval was 13 s.

[0130] Figure 15 As shown in FIG. 6, the characteristic peak of Rhb is located at 552 nm, and after the catalyst was added, the characteristic peak disappeared after 117 s, indicating that the Rhb was completely degraded.

[0131] The results show that the C@Cu provided by the application exhibits significant application performance in catalyzing the degradation of organic pollutants.

[0132] Comparative Example 8: C nanospheres (the sample obtained in Comparative Example 1) catalyzing the degradation of Rhb

[0133] ​1) At room temperature, prepare a solution of Rhb with a concentration of 0.1 mmol / L, take 3.4 mL and place it in a cuvette, measure the absorption spectrum of the initial solution (spectrum range: 400-650 nm), and take out the cuvette after the test is completed;

[0134] 2) Prepare a suspension of the C nanospheres obtained in Comparative Example 1 with a concentration of 7.5 mmol / L, take 0.2 mL of the suspension after uniform ultrasonic treatment, and use a dropper to drop it into a cuvette containing 3.4 mL of Rhb (0.1 mmol / L) and again ultrasonic treatment until adsorption equilibrium is reached, to obtain a mixed solution 1;

[0135] 3) Half the volume of the mixed solution 1 in the cuvette (to 1.8 mL), pour it into the cuvette again, quickly add a NaBH4 solution with a concentration of 40 mmol / L and a volume of 0.7 mL, continuously measure the spectrum until Rhb is completely degraded, and the single collection time interval is 20 s.

[0136] As Figure 16 described, the C nanospheres obtained in Comparative Example 1 have almost no catalytic performance for Rhb degradation, and the characteristic peak at 552 nm does not decrease after 160 s of reaction time, proving that Rhb has not been degraded.

[0137] Comparative Example 9: Cu nanocrystals (sample obtained in Comparative Example 3) catalyze Rhb degradation

[0138] 1) At room temperature, prepare a solution of Rhb with a concentration of 0.1 mmol / L, take 3.4 mL and place it in a cuvette, measure the absorption spectrum of the initial solution (spectrum range: 400-650 nm), and take out the cuvette after the test is completed;

[0139] 2) Prepare a suspension of the Cu element obtained in Comparative Example 3 with a concentration of 7.5 mmol / L, take 0.2 mL of the suspension after uniform ultrasonic treatment, and use a dropper to drop it into a cuvette containing 3.4 mL of Rhb (0.1 mmol / L) and again ultrasonic treatment until adsorption equilibrium is reached, to obtain a mixed solution 1;

[0140] 3) Half the volume of the mixed solution 1 in the cuvette (to 1.8 mL), pour it into the cuvette again, quickly add a NaBH4 solution with a concentration of 40 mmol / L and a volume of 0.7 mL, continuously measure the spectrum until Rhb is completely degraded, and the single collection time interval is 26 s.

[0141] Figure 17As shown, after the sample obtained in Comparative Example 3 was catalytically dyed, the characteristic peak at 182 s disappeared after Rhb, indicating that the dye Rhb was completely degraded. Compared with the reaction time (117 s) of Application Example 3, the degradation time of Rhb was prolonged. It is proved that the C@Cu provided in Example 1 has better catalytic activity in catalyzing the degradation of dyes.

[0142] In summary, the application provides a Cu-modified C nanosphere for catalytic degradation of synergistic organic dyes. It should be noted that the above is the preferred embodiment of the application. For those skilled in the art, without departing from the principles of the application, a number of improvements and refinements can be made, which are also considered within the scope of protection of the application.

Claims

1. A method for synergistically catalytic degradation of organic dyes by Cu-modified C nanospheres, characterized in that, The preparation method of the Cu-modified C nanosphere C@Cu is as follows: 1) dilute the concentration of dilute hydrochloric acid to 0.5-0.6 mol / L using deionized water, stir and mix uniformly to obtain a mixed solution 1; 2) weigh ascorbic acid according to the proportion, add it to the mixed solution 1, stir uniformly at room temperature, and after the ascorbic acid is completely dissolved, obtain a mixed solution 2; 3) pour the mixed solution 2 into a reaction kettle, heat to 120°C and react for 1 hour; 4) select to use an ethanol solution, KOH powder as the solute, mix according to the proportion, stir uniformly to make the KOH powder completely dissolved, and mark it as solution 3; 5) after the reaction kettle is heated, cool it to room temperature naturally, pour the reaction product of the heated mixed solution 2 into the solution 3, ultrasonic dispersion for 30 minutes, and obtain a mixed solution 4; 6) configure a NaBH4 solution with deionized water as the solvent, add it to the mixed solution 4 according to the proportion, and obtain a mixed solution 5; 7) configure a CuCl2 aqueous solution with deionized water as the solvent, after stirring uniformly, add it dropwise to the mixed solution 5 in 8 times, the interval of each dropwise adding time is 1 minute, and obtain a mixed solution 6; 8) continue to ultrasonic react the mixed solution 6 at 40°C for 20 minutes; 9) centrifugal separate the ultrasonic reacted mixed solution 6, wash the precipitate with deionized water and ethanol 1-3 times, then perform centrifugal separation again, dry at 40-50°C for 12 hours, and the obtained powder is C@Cu; Step 2) the mass of ascorbic acid added to each milliliter of the mixed solution 1 is in the range of 0.042-0.044 g; Step 4) the mass of KOH contained in each milliliter of the ethanol solution is 0.028 g; Step 6) the concentration of the NaBH4 aqueous solution is 0.075 g / mL, and the volume ratio of the mixed solution 4 to the NaBH4 aqueous solution is 4:1-5:1; Step 7) the concentration of the configured CuCl2 aqueous solution is 0.28-0.32 mol / L, and the volume ratio of the mixed solution 5 to the CuCl2 aqueous solution is 26:1-28:1.

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