A kind of high-efficiency activation of persulfate by carbon-coated copper oxide NC / CuO

Abstract

The application provides a method for treating organic wastewater by using carbon-coated copper oxide NC / CuO to activate persulfate efficiently, and comprises the following steps: S1, blending Zn(NO3)2.6H2O and 2-methyl imidazole to obtain a precursor A; S2, blending the precursor A and Cu(NO3)2.3H2O, stirring and reacting, and calcining to obtain carbon-coated copper oxide NC / CuO; S3, adding persulfate and the carbon-coated copper oxide NC / CuO into wastewater containing organic pollutants to perform wastewater treatment reaction. The method utilizes the limitation effect of the interface of NC / CuO to enrich and catalyze the persulfate in the aqueous solution to generate high-valence metal Cu(III) species, so that the pollutants in the water are oxidized, degraded and removed through single electron transfer and hydrogen extraction and other ways; meanwhile, the method has the advantages of simple process, mild conditions, easy control, wide adaptation range of wastewater pH value, good treatment effect and the like.

Description

[0001] Methods for treating organic wastewater Technical Field

[0002] This invention relates to the field of water pollution control technology, and in particular to a method for treating organic wastewater by using carbon-coated copper oxide (NC / CuO) to efficiently activate persulfate. Background Technology

[0003] With the rapid industrial development in recent years, large amounts of organic matter have been discharged into environmental water bodies, causing serious water pollution problems and threatening human health and living standards. Many methods exist for treating water pollution, among which advanced oxidation technologies (AOTs) can generate highly oxidizing reactive oxygen species (ROS) through chain reactions, and have been proven by continuous research to be an effective method for treating new pollutants. However, in heterogeneous Fenton systems based on peroxymonosulfate, the short half-life of ROS (·OH = 1 μs, SO4·- = 30-40 μs) limits their mass transfer distance in aqueous solutions, resulting in low oxidant utilization efficiency.

[0004] Space confinement strategies have been widely applied in numerous fields, particularly when reactants are confined within nanoscale reactors (cavities, pores, nanocages, interfaces, etc.). This significantly reduces mass transfer distances, and the physicochemical properties of atoms, molecules, and clusters may change within the confined space, leading to new chemical reaction pathways and increased reaction rates. Under space-confined conditions, nanoreactors may interact with guest molecules, causing a rearrangement of their intrinsic electron distribution, optimizing their own electronic structure, and further promoting the reaction. In recent years, spatial confinement strategies have gradually emerged in the environmental field. For example, (1) in a confined environment at the nanoscale, molecules, ions, and other substances undergo deformation and other property changes due to the confinement effect, which may lead to changes in chemical reactions. For example, when the active sites are located at the catalyst surface and inside the catalyst, the generated ROS will change, leading to changes in the reaction pathway and products; (2) the spatial effect can effectively regulate the electron transfer rate in the reaction. For example, as the curvature of the catalyst changes, the bond length and bond angle of the chemical bonds may change, resulting in a different electron distribution of the catalyst than at the surface and interface, thus affecting the electron transport capacity of the catalytic reaction; (3) the spatial confinement effect usually means a short mass transfer distance. Spatial confinement leads to the enrichment of reactants and the increase of the diffusion rate in the channel, which means that ROS can be utilized more effectively, thereby further improving the catalytic reaction rate. However, most spatial confinement strategies are currently focused on closed spaces. Open interfaces and guest molecules also have similar interactions, but there is little research on the confinement effect of open interfaces, which is not as in-depth as the research on nanoreactors.

[0005] Therefore, by synthesizing ZIF-8(Cu) through post-synthetic modification and then pyrolyzing and calcining it, carbon-coated copper oxide nanospheres (NC / CuO) were synthesized as an effective catalyst for peroxymonosulfate-AOTs, which helps us understand the application of interfacial confinement effects in the treatment of organic wastewater. To date, the application of the interfacial confinement effect in carbon-coated copper oxide for water treatment has not been reported in the literature or patents.

[0006] In conclusion, there is an urgent need to develop a new technical solution to address the problems existing in the current technology. Summary of the Invention

[0007] Based on this, the present invention provides a method for treating organic wastewater by using carbon-coated copper oxide (NC / CuO) to efficiently activate persulfate. This method utilizes the confinement effect at the NC / CuO interface to enrich and catalyze the persulfate in the aqueous solution to generate high-valence metal Cu(III) species. Pollutants in the water are oxidized, degraded, and removed through single-electron transfer and hydrogen extraction. At the same time, this method has the advantages of simple process, mild conditions, easy control, wide adaptability to wastewater pH value, and good treatment effect.

[0008] One object of the present invention is to provide a method for treating organic wastewater by using carbon-coated copper oxide (NC / CuO) to efficiently activate persulfate, comprising the following steps:

[0009] S1. Zn(NO3)·6H2O and 2-methylimidazole are mixed and reacted to obtain precursor A;

[0010] S2. The precursor A and Cu(NO3)2·3H2O are mixed, stirred and reacted, and then calcined under inert gas protection to obtain carbon-coated copper oxide NC / CuO.

[0011] S3. Add persulfate and the carbon-coated copper oxide NC / CuO to the wastewater containing organic pollutants to carry out the wastewater treatment reaction.

[0012] Furthermore, the carbon-coated copper oxide NC / CuO is used as a catalyst (i.e., an activator), and persulfate is used as an oxidant.

[0013] Furthermore, the mass ratio of the precursor A to Cu(NO3)2·3H2O is 1:0.1-6.

[0014] Furthermore, the precursor A is ZIF-8, which is prepared using Zn(NO3)·6H2O as the Zn source and 2-methylimidazole as the organic ligand.

[0015] Furthermore, the persulfate is selected from one or more of potassium persulfate, sodium persulfate, or ammonium persulfate.

[0016] Furthermore, the persulfate is potassium persulfate.

[0017] Furthermore, the initial pH value of the wastewater containing organic pollutants is 6-7.

[0018] Furthermore, the molar ratio of the persulfate to the organic pollutant is 10-200:1.

[0019] Furthermore, the mass ratio of the carbon-coated copper oxide (NC / CuO) to the organic pollutants is 20-200:1.

[0020] Furthermore, in step S2, the stirring reaction time is 10-15 hours.

[0021] Furthermore, in step S2, the calcination temperature is 400-600℃ and the time is 10-60 min.

[0022] Furthermore, in step S3, the wastewater treatment reaction time is 30-60 minutes.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention provides a method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) to efficiently activate persulfate. This method utilizes the confinement effect at the NC / CuO interface to enrich and catalyze the production of high-valence metal Cu(III) species from persulfate in aqueous solution. Pollutants in the water are oxidized, degraded, and removed through single-electron transfer and hydrogen extraction. Compared to conventional copper oxides, NC / CuO easily enriches reactants due to surface electron rearrangement, exhibiting an interface confinement effect similar to nano-confinement. The sample surface interacts with guest molecules, optimizing its own electronic structure and further promoting the reaction. As an electron donor, NC / CuO can complex with persulfate to produce Cu(III) and singlet oxygen, resulting in high persulfate utilization efficiency, fast reaction rate, and high pollutant and COD degradation rates. This invention, through the interface confinement effect, regulates the reaction pathway, producing Cu(III) species, further accelerating the reaction rate, and increasing the COD removal rate from 9.4% to 71.2%. This invention provides methodological and theoretical support for the application of interface confinement effects in water pollution control technology.

[0025] 2. The carbon-coated copper oxide NC / CuO surface of this invention has a more positive Cu active site potential. Compared with existing traditional copper oxides, the catalyst exhibits better structure and activity, stronger activity, and can activate persulfate, generating a large amount of Cu(III) and... through a non-radical pathway. 1 O2 has high oxidant utilization efficiency and pollutant removal efficiency.

[0026] 3. The carbon-coated copper oxide (NC / CuO) activation method for generating active free radicals using this invention has shown excellent results in treating thiamethoxam (THM) wastewater with a pH range of 3-11. This indicates that the method of this invention has a wide range of adaptability to wastewater pH values ​​and saves the cost of pre-adjusting the wastewater pH to acidity.

[0027] 4. The method for treating organic wastewater by carbon-coated copper oxide (NC / CuO) activation persulfate provided by this invention is simple in process, easy to operate, mild in conditions, and has good treatment effect, making it suitable for the treatment of various types of organic wastewater. Attached Figure Description

[0028] Figure 1 The transmission electron microscope (HR-TEM) image of NC / CuO-3 prepared in Example 1 is shown;

[0029] Figure 2 The X-ray diffraction (XRD) pattern of NC / CuO-3 prepared in Example 1 is shown.

[0030] Figure 3 The photoelectron spectroscopy (XPS) spectra of NC / CuO-3 prepared in Example 1 and its reaction with THM and PMS are shown.

[0031] in,

[0032] Figure 3 (a) shows the Cu2p orbital photoelectron spectrum of NC / CuO-3 prepared in Example 1;

[0033] Figure 3 (b) shows the Cu2p orbital photoelectron spectrum of NC / CuO-3 prepared in Example 1 after reaction with THM and PMS;

[0034] Figure 4 Electron paramagnetic resonance (EPR) spectra of NC / CuO-3 / PMS / THM prepared in Example 1 compared with CuO / PMS / THM are shown.

[0035] in,

[0036] Figure 4 (a) shows the EPR spectra of NC / CuO-3 / PMS / THM and CuO / PMS / THM prepared in Example 1 when DMPO is used as a trapping agent;

[0037] Figure 4 (b) shows the EPR spectra of NC / CuO-3 / PMS / THM and CuO / PMS / THM prepared in Example 1 when TEMP is used as a trapping agent;

[0038] Figure 5The in-situ Raman spectra of NC / CuO-3 prepared in Example 1 in different reaction systems are shown. Detailed Implementation

[0039] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0041] Considering that neonicotinoids are frequently used as pesticides in agriculture, they are emerging environmental pollutants closely related to daily human life. They can enter water bodies and be detected in the environment through various pathways such as insecticides and food. Although the emission concentration is low, their wide distribution, long persistence in the environment, and easy participation in the geochemical water cycle and accumulation and amplification in organisms lead to the widespread dissemination and spread of drug-resistant bacteria and genes, causing irreversible damage (such as cancer) to the reproductive, nervous, digestive (liver), and urinary (kidney) systems of mammals, directly threatening human health. Therefore, this invention selects thiamethoxam, the neonicotinoid pollutant with the highest detection frequency in surface water in my country, as the target pollutant. Thiamethoxam-simulated wastewater is used as the wastewater to be treated, and the degree of thiamethoxam degradation represents the treatment efficiency of the organic wastewater.

[0042] The chemical reagents used in the embodiments and test examples of this invention, such as zinc nitrate hexahydrate (Zn(NO3)·6H2O), 2-methylimidazole, methanol (MeOH), potassium persulfate (PMS), and thiamethoxam (THM), are all analytical grade; and the water used is deionized water.

[0043] The method for detecting the residual THM concentration in the embodiments and test examples of this invention is as follows: Model: Agilent 1260; Column: C18 (2.1*100); Mobile phase: formic acid water (1%): methanol = 30:70; Flow rate: 1 ml / min.

[0044] In the NC / CuO-x embodiment of the present invention, x represents the mass ratio of Cu(NO3)2·3H2O to ZIF-8.

[0045] In the NC / CuO provided by this invention, the reaction activity is best when x is 3. Therefore, in the test examples of this invention, unless otherwise specified, NC / CuO refers to NC / CuO-3.

[0046] Example 1

[0047] A method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate includes the following steps:

[0048] S1. Add Zn(NO3)·6H2O (2790mg) to methanol (100mL), stir for 30min, and after Zn(NO3)·6H2O is completely dissolved, add 2-methylimidazole (3080mg), then add methanol (100mL), let stand overnight, and centrifuge to obtain ZIF-8.

[0049] S2. Place the ZIF-8 (50mg) in a 100mL beaker, add methanol (30mL) and Cu(NO3)2·3H2O (150mg), stir for 12h, wash with deionized water and methanol, vacuum dry at 80℃ for 48h, then place the dried sample in a tube furnace, raise the temperature from room temperature to 500℃ at a rate of 10℃ / min under a nitrogen atmosphere, calcine for 30min, and obtain carbon-coated copper oxide NC / CuO-3.

[0050] S3. Potassium persulfate (2.5 mg) and carbon-coated copper oxide (NC / CuO-3) (20 mg) were added to 50 mL of wastewater containing THM (5 mg / L) with an initial pH of 7. The wastewater treatment reaction was carried out with stirring at 25℃ and 500 rpm for 60 min. After the reaction, the residual THM concentration was measured to be 0.06 mg / L, with a removal rate of 98.8%. THM was fully oxidized and degraded, and the wastewater was treated.

[0051] Figure 1 The image shown is a transmission electron microscope (HR-TEM) image of NC / CuO-3 prepared in Example 1; by Figure 1 As can be seen, CuO lattice fringes are displayed on the catalyst surface, and CuO is clearly coated by the carbon substrate, which proves the successful synthesis of the material of the present invention.

[0052] Figure 2 The X-ray diffraction (XRD) pattern of NC / CuO-3 prepared in Example 1 is shown; Figure 2 As can be seen, the characteristic peak of copper oxide appears in the figure, and the characteristic peak of ZIF-8 gradually weakens, further proving that CuO and carbon substrate are composited to form NC / CuO-3;

[0053] Figure 3 The photoelectron spectroscopy (XPS) spectra of NC / CuO-3 prepared in Example 1 and its reaction with THM and PMS are shown.

[0054] in,

[0055] Figure 3(a) shows the Cu2p orbital photoelectron spectrum of NC / CuO-3 prepared in Example 1;

[0056] Figure 3 (b) shows the Cu2p orbital photoelectron spectrum of NC / CuO-3 prepared in Example 1 after reaction with THM and PMS;

[0057] according to Figure 3 (a) and Figure 3 (b) By comparison, it can be found that after the reaction in the NC / CuO-3 / PMS / THM system, the binding energy of Cu sites increases compared to before the reaction, indicating that the electron density around them decreases and the valence state of Cu sites increases, indicating that Cu(III) may have been formed, leading to the increase in the valence state of Cu sites.

[0058] Figure 4 Electron paramagnetic resonance (EPR) spectra of NC / CuO-3 / PMS / THM prepared in Example 1 compared with CuO / PMS / THM are shown.

[0059] in,

[0060] Figure 4 (a) shows the EPR spectra of NC / CuO-3 / PMS / THM and CuO / PMS / THM prepared in Example 1 when DMPO is used as a trapping agent;

[0061] Figure 4 (b) shows the EPR spectra of NC / CuO-3 / PMS / THM and CuO / PMS / THM prepared in Example 1 when TEMP is used as a trapping agent;

[0062] according to Figure 4 (a) It can be observed that pure CuO does not show adduct peaks, while NC / CuO-3 shows adduct peaks, indicating that NC / CuO-3 / PMS / THM can produce oxidizing species. However, observation of the spectrum shows that the peak shape does not belong to DMPO-·OH and DMPO-SO4·-, because its oxidizing power is stronger and DMPO reacts to generate DMPO-X, indicating that a new active species Cu(Ⅲ) may have been generated; according to Figure 4 (b) It can be found that CuO and NC / CuO-3 have the same peak shape. The signal peak intensity of CuO is higher than that of NC / CuO-3, but the activity effect of NC / CuO-3 is much higher than that of CuO, which suggests that there may be the role of other active species.

[0063] Figure 5 The in-situ Raman spectra of NC / CuO-3 prepared in Example 1 in different reaction systems are shown.

[0064] according to Figure 5 It can be observed that after the addition of PMS, the in-situ Raman spectrum at 616 cm⁻¹... -1 A new peak appeared at the point, which is a characteristic peak of metastable Cu(III), further illustrating the formation of Cu(III).

[0065] Example 2

[0066] A method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate includes the following steps:

[0067] S1. Add Zn(NO3)·6H2O (2790mg) to methanol (100mL), stir for 30min, and after Zn(NO3)·6H2O is completely dissolved, add 2-methylimidazole (3080mg), then add methanol (100mL), let stand overnight, and centrifuge to obtain ZIF-8.

[0068] S2. Place the ZIF-8 (50mg) in a 100mL beaker, add methanol (30mL) and Cu(NO3)2·3H2O (5mg), stir for 12h, wash with deionized water and methanol, vacuum dry at 80℃ for 48h, then place the dried sample in a tube furnace, raise the temperature from room temperature to 500℃ at a rate of 10℃ / min under a nitrogen atmosphere, calcine for 30min, and obtain carbon-coated copper oxide NC / CuO-0.1;

[0069] S3. Add potassium persulfate (2.5 mg) and carbon-coated copper oxide NC / CuO-0.1 (20 mg) to 50 mL of wastewater containing THM (5 mg / L) with an initial pH of 7. Stir the mixture for 60 min at 25 °C and 500 rpm for wastewater treatment.

[0070] Example 3

[0071] A method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate includes the following steps:

[0072] S1. Add Zn(NO3)·6H2O (2790mg) to methanol (100mL), stir for 30min, and after Zn(NO3)·6H2O is completely dissolved, add 2-methylimidazole (3080mg), then add methanol (100mL), let stand overnight, and centrifuge to obtain ZIF-8.

[0073] S2. Place the ZIF-8 (50mg) in a 100mL beaker, add methanol (30mL) and Cu(NO3)2·3H2O (25mg), stir for 12h, wash with deionized water and methanol, vacuum dry at 80℃ for 48h, then place the dried sample in a tube furnace, raise the temperature from room temperature to 500℃ at a rate of 10℃ / min under a nitrogen atmosphere, calcine for 30min, and obtain carbon-coated copper oxide NC / CuO-0.5;

[0074] S3. Add potassium persulfate (2.5 mg) and carbon-coated copper oxide NC / CuO-0.5 (20 mg) to 50 mL of wastewater containing THM (5 mg / L) with an initial pH of 7. Stir the mixture for 60 min at 25 °C and 500 rpm for wastewater treatment.

[0075] Example 4

[0076] A method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate includes the following steps:

[0077] S1. Add Zn(NO3)·6H2O (2790mg) to methanol (100mL), stir for 30min, and after Zn(NO3)·6H2O is completely dissolved, add 2-methylimidazole (3080mg), then add methanol (100mL), let stand overnight, and centrifuge to obtain ZIF-8.

[0078] S2. Place the ZIF-8 (50mg) in a 100mL beaker, add methanol (30mL) and Cu(NO3)2·3H2O (75mg), stir for 12h, wash with deionized water and methanol, vacuum dry at 80℃ for 48h, then place the dried sample in a tube furnace, raise the temperature from room temperature to 500℃ at a rate of 10℃ / min under a nitrogen atmosphere, calcine for 30min, and obtain carbon-coated copper oxide NC / CuO-1.5;

[0079] S3. Add potassium persulfate (2.5 mg) and carbon-coated copper oxide NC / CuO-1.5 (20 mg) to 50 mL of wastewater containing THM (5 mg / L) with an initial pH of 7. Stir the mixture for 60 min at 25 °C and 500 rpm for wastewater treatment.

[0080] Example 5

[0081] A method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate includes the following steps:

[0082] S1. Add Zn(NO3)·6H2O (2790mg) to methanol (100mL), stir for 30min, and after Zn(NO3)·6H2O is completely dissolved, add 2-methylimidazole (3080mg), then add methanol (100mL), let stand overnight, and centrifuge to obtain ZIF-8.

[0083] S2. Place the ZIF-8 (50mg) in a 100mL beaker, add methanol (30mL) and Cu(NO3)2·3H2O (300mg), stir for 12h, wash with deionized water and methanol, vacuum dry at 80℃ for 48h, then place the dried sample in a tube furnace, raise the temperature from room temperature to 500℃ at a rate of 10℃ / min under a nitrogen atmosphere, calcine for 30min, and obtain carbon-coated copper oxide NC / CuO-6;

[0084] S3. Add potassium persulfate (2.5 mg) and carbon-coated copper oxide NC / CuO-6 (20 mg) to 50 mL of wastewater containing THM (5 mg / L) with an initial pH of 7. Stir the mixture for 60 min at 25 °C and 500 rpm for wastewater treatment.

[0085] Test Example 1

[0086] Test method:

[0087] Using NC / CuO-3, ZIF-8, and CuO prepared in Example 1 as catalysts and PMS as oxidant, simulated organic wastewater with an initial THM concentration of 5 mg / L was prepared without adjusting the pH of the wastewater.

[0088] Five 100mL beakers were used as reaction vessels, and 50mL of THM wastewater was added to each vessel. Five treatment groups were set up: Treatment group 1: NC / CuO-3 was added (until the catalyst concentration in the solution was 0.4mg / mL) and PMS (2.5mg, 0.05mg / mL); Treatment group 2: NC / CuO-3 was added only (until the catalyst concentration in the solution was 0.4mg / mL); Treatment group 3: PMS (2.5mg, 0.05mg / mL) was added only; Treatment group 4: CuO was added (until the catalyst concentration in the solution was 0.4mg / mL) and PMS (2.5mg, 0.05mg / mL); Treatment group 5: ZIF-8 was added (until the catalyst concentration in the solution was 0.4mg / mL) and PMS (2.5mg, 0.05mg / mL).

[0089] Following the above treatment group, after adding the catalyst to the THM wastewater (if not set, it is not added), the adsorption reaction is carried out by stirring thoroughly on a magnetic stirrer at a temperature of 25℃ and a rotation speed of 500rpm. After 30 minutes of adsorption reaction, PMS is added (if not set, it is not added). Samples are taken at 0 min, 1 min, 2 min, 5 min, 10 min, 20 min, 30 min and 60 min of reaction and the residual THM concentration is measured to calculate the THM removal rate.

[0090] The test results are shown in Table 1:

[0091] Table 1. Test results of different systems for treating THM wastewater

[0092]

[0093] Here, -30min represents the time when the adsorption reaction begins.

[0094] Test results showed that neither the NC / CuO-3 system (treatment group 2) nor the PMS system (treatment group 3) could effectively remove THM from the wastewater. However, the NC / CuO-3-activated PMS system (treatment group 1) showed a significant effect on the oxidative degradation of THM. After 20 minutes of reaction, the THM degradation rate reached 94.77%, and after 60 minutes of reaction, THM was almost completely degraded. This indicates that the reactive oxygen species generated by NC / CuO-3-activated PMS enabled the rapid and effective degradation of the pollutant THM.

[0095] Test Example 2

[0096] Test method: NC / CuO-3 prepared in Example 1 was used as the catalyst, and PMS was used as the oxidant. Simulated organic wastewater with an initial THM concentration of 5 mg / L was prepared without adjusting the pH of the wastewater.

[0097] Five 100mL beakers were used as reaction vessels, and 50mL of THM wastewater was added to each vessel. Five treatment groups were set up as follows: Treatment group 1: NC / CuO-3 was added (until the catalyst concentration in the solution was 0.1mg / mL); Treatment group 2: NC / CuO-3 was added (until the catalyst concentration in the solution was 0.2mg / mL); Treatment group 3: NC / CuO-3 was added (until the catalyst concentration in the solution was 0.4mg / mL); Treatment group 4: NC / CuO-3 was added (until the catalyst concentration in the solution was 0.6mg / mL); Treatment group 5: NC / CuO-3 was added (until the catalyst concentration in the solution was 1mg / mL).

[0098] According to the above treatment group, after adding the catalyst to the THM wastewater, the adsorption reaction was carried out by stirring thoroughly on a magnetic stirrer at a temperature of 25℃ and a rotation speed of 500 rpm. After 30 min of adsorption reaction, PMS was added (until the PMS concentration in the solution was 0.05 mg / mL). Samples were taken at 0 min, 1 min, 2 min, 5 min, 10 min, 20 min, 30 min and 60 min of reaction and the residual THM concentration was measured. The THM removal rate was calculated.

[0099] The test results are shown in Table 2:

[0100] Table 2. Test results of THM wastewater treated with different concentrations of NC / CuO-3.

[0101]

[0102] Here, -30min represents the time when the adsorption reaction begins.

[0103] The test results show that the dosage of NC / CuO-3 affects the efficiency of PMS in oxidizing and degrading THM in simulated wastewater. Within a certain range, the THM degradation rate increases with the increase of catalyst dosage: when the catalyst dosage is 0.1 mg / mL, the THM removal rate reaches 94.17% after 60 min of reaction; when the dosage is increased to 0.6 mg / mL, the THM removal rate increases to 99.83% after the same reaction time; however, when the dosage is further increased to 1.0 mg / mL, the THM removal rate decreases by 13.13% after 5 min. This indicates that under these reaction conditions, an excess of NC / CuO-3 in the solution affects the mass transfer process of THM and even active species in the solution, thus reducing the THM removal rate throughout the entire reaction process. The above results indicate that the rate and extent of the oxidative degradation reaction of the target pollutants can be controlled by adjusting the dosage of NC / CuO. In practical applications, the dosage of NC / CuO can be selected according to the initial pollutant concentration in the wastewater and the required wastewater treatment efficiency, so as to maximize material savings and reduce treatment costs.

[0104] Test Example 3

[0105] Test method: NC / CuO-3 prepared in Example 1 was used as the catalyst, and PMS was used as the oxidant. Simulated organic wastewater with an initial THM concentration of 5 mg / L was prepared without adjusting the pH of the wastewater.

[0106] Five 100mL beakers were used as reaction vessels. 50mL of THM wastewater and NC / CuO-3 were added to each reaction vessel (until the catalyst concentration in the solution was 0.4mg / mL). The adsorption reaction was carried out for 30min by stirring on a magnetic stirrer at a temperature of 25℃ and a rotation speed of 500rpm.

[0107] Five treatment groups were set up: Treatment group 1: PMS was added (to a concentration of 0.01 mg / mL); Treatment group 2: PMS was added (to a concentration of 0.025 mg / mL); Treatment group 3: PMS was added (to a concentration of 0.05 mg / mL); Treatment group 4: PMS was added (to a concentration of 0.1 mg / mL); Treatment group 5: PMS was added (to a concentration of 0.2 mg / mL).

[0108] According to the above treatment group, PMS was added to the solution after 30 min of adsorption reaction for reaction. Samples were taken and the residual THM concentration was measured at 0 min, 1 min, 2 min, 5 min, 10 min, 20 min, 30 min and 60 min of reaction, and the THM removal rate was calculated.

[0109] The test results are shown in Table 3:

[0110] Table 3. Test results of THM wastewater treated with different concentrations of PMS

[0111]

[0112] Here, -30min represents the time when the adsorption reaction begins.

[0113] Test results show that the dosage of PMS affects the efficiency of the system in oxidizing and degrading simulated THM wastewater. As the dosage of PMS gradually increases, the degradation rate of THM increases accordingly. When the PMS dosage is 0.05 mg / mL, nearly 95% of THM can be removed after 60 minutes of reaction. When the PMS dosage is 0.2 mg / mL, the THM degradation rate reaches 97.9% after 60 minutes of reaction, but the PMS reaction rate does not increase significantly, indicating that PMS is in excess at this point. These results indicate that excessive PMS dosage does not significantly accelerate the reaction process, resulting in waste of oxidant and reduced efficiency in THM oxidation. The results also show that the NC / CuO provided by this invention has good structure-activity relationship, high PMS decomposition efficiency and utilization, avoiding the problems of PMS waste and secondary pollution caused by the poor structure-activity relationship of traditional PMS catalysts. When treating actual wastewater, the dosage of PMS should be selected based on the initial pollutant concentration and treatment efficiency requirements to save reactants and reduce treatment costs.

[0114] Test Example 4

[0115] Test method: Using NC / CuO-3 prepared in Example 1 as the catalyst and PMS as the oxidant, simulated organic wastewater with an initial THM concentration of 5 mg / L was prepared, and the pH of the wastewater was adjusted.

[0116] Five 100mL beakers were used as reaction vessels, and 50mL of THM wastewater was added to each vessel. Five treatment groups were set up as follows: Treatment group 1: the initial pH of the THM wastewater was adjusted to 3; Treatment group 2: the initial pH of the THM wastewater was adjusted to 5; Treatment group 3: the initial pH of the THM wastewater was adjusted to 7; Treatment group 4: the initial pH of the THM wastewater was adjusted to 9; Treatment group 5: the initial pH of the THM wastewater was adjusted to 11.

[0117] Following the above treatment group, after adding the catalyst to the THM wastewater (until the PMS concentration in the solution is 0.4 mg / mL), the adsorption reaction was carried out by stirring thoroughly on a magnetic stirrer at a temperature of 25℃ and a rotation speed of 500 rpm. After 30 min of adsorption reaction, PMS (until the PMS concentration in the solution is 0.05 mg / mL) was added. Samples were taken at 0 min, 1 min, 2 min, 5 min, 10 min, 20 min, 30 min and 60 min of reaction, and the residual THM concentration was measured to calculate the THM removal rate.

[0118] The test results are shown in Table 4:

[0119] Table 4. Test results of THM wastewater treated with different initial pH values.

[0120]

[0121] Here, -30min represents the time when the adsorption reaction begins.

[0122] Test results show that the degradation rate of pollutants does not change significantly when the pH range is 5-9, and THM is almost completely degraded after 60 minutes of reaction. When the initial pH decreases to 3, both the removal rate and efficiency of THM decrease. It was observed that the removal rate and efficiency of THM further increase under alkaline conditions at pH=11. However, since the THM removal rate can reach 83.9% after 60 minutes of reaction at pH=3, this indicates that the system still has a strong oxidative degradation capacity for strongly acidic and alkaline wastewater. Therefore, the system has a very wide pH adaptability range for wastewater, but it is most effective in treating organic wastewater with an initial pH range of 5-11.

[0123] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0124] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate, characterized in that, Includes the following steps: S1. Zn(NO3)·6H2O and 2-methylimidazole are mixed and reacted to obtain precursor A; S2. The precursor A and Cu(NO3)2·3H2O are mixed, stirred and reacted, and then calcined under inert gas protection to obtain carbon-coated copper oxide NC / CuO. S3. Add persulfate and the carbon-coated copper oxide NC / CuO to the wastewater containing organic pollutants to carry out the wastewater treatment reaction; The precursor A is ZIF-8; The mass ratio of the precursor A to Cu(NO3)2·3H2O is 1:0.1-6; In step S2, the calcination temperature is 400-600℃ and the time is 10-60 min.

2. The method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate according to claim 1, characterized in that, The persulfate is selected from one or more of potassium persulfate, sodium persulfate, or ammonium persulfate.

3. The method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate according to claim 2, characterized in that, The persulfate is potassium persulfate.

4. The method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate according to claim 1, characterized in that, The initial pH value of the wastewater containing organic pollutants is 6-7.

5. The method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate according to claim 1, characterized in that, The molar ratio of persulfate to organic pollutant is 10-200:

1.

6. The method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate according to claim 1, characterized in that, The mass ratio of carbon-coated copper oxide (NC / CuO) to organic pollutants is 20-200:

1.

7. The method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate according to claim 1, characterized in that, In step S2, the stirring reaction takes 10-15 hours.

8. The method for treating organic wastewater using carbon-coated copper oxide (NC / CuO) for efficient activation of persulfate according to claim 1, characterized in that, In step S3, the wastewater treatment reaction time is 30-60 min.

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