A spatially confined copper-based catalyst for activating persulfate to degrade organic pollutants in water, and a preparation method and application thereof

Abstract

This invention discloses a method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water: (1) Dissolve nano-oxide materials and carbon sources in a solvent, stir thoroughly, centrifuge, dry, and then calcine the resulting powder at high temperature. After cooling, etch with an etching solution, centrifuge, and dry to obtain spatially confined carbon spheres; (2) Disperse the spatially confined carbon spheres obtained in step (1) with copper salt and precipitant in water, centrifuge, dry, and then calcine the resulting powder at high temperature. After cooling, the spatially confined copper-based catalyst is obtained. This invention also includes the spatially confined copper-based catalyst prepared by the above method and its application in activating persulfate degradation of organic pollutants in water. By constructing a carbon sphere-CuO heterostructure catalytic structure with spatial confinement effect, the synergistic effect of spatial confinement, interfacial electronic coupling, and active sites is fully utilized, achieving multiple synergistic regulation of pollutant enrichment, rapid electron transport, and selective activation of persulfate. Compared with traditional copper-based catalytic systems, this invention can effectively regulate the generation pathway of reactive oxygen species, significantly improve the utilization efficiency of persulfate and the selectivity of pollutant degradation, and significantly enhance the stability, anti-interference ability and recycling performance of the catalyst. It can be widely used in the deep purification of recalcitrant organic pollutants such as pesticides, antibiotics, and phenols, as well as in the treatment of complex wastewater.

Description

Technical Field

[0001] This invention relates to the fields of environmental functional materials and advanced oxidation technologies, and in particular to the preparation of a spatially confined copper-based catalyst and its application in the persulfate-activated degradation of organic pollutants in water. Background Technology

[0002] With the rapid development of the global economy and the continuous growth of the population, water pollution has become a severe global environmental problem, seriously threatening human health and the balance of ecosystems. The large-scale discharge of industrial wastewater, agricultural wastewater, and domestic sewage has led to a continuous increase in the types and quantities of organic pollutants in water bodies, with persistent organic pollutants, such as pesticides, being particularly prominent. These pollutants are generally characterized by high toxicity, high stability, and difficulty in natural degradation. Once they enter water bodies, they remain for extended periods, posing a potential threat to aquatic life and human health. For example, atrazine, a widely used herbicide, leaves large amounts of residues in the aquatic environment, easily causing ecosystem imbalance and posing a serious threat to the safety of aquatic life and human health.

[0003] Traditional water treatment technologies, such as physical adsorption, flocculation and sedimentation, and biodegradation, have significant limitations in treating these recalcitrant organic pollutants: physical adsorption can remove some pollutants, but its adsorption capacity is limited and the adsorbent is difficult to regenerate; flocculation and sedimentation are mainly effective for suspended and colloidal particles and are less effective at removing dissolved organic pollutants; and biodegradation has a long reaction cycle and is subject to high requirements on the type and concentration of pollutants, making it difficult to cope with complex and ever-changing actual water pollution conditions.

[0004] To overcome the aforementioned technological bottlenecks, researchers have begun exploring new, more efficient, and environmentally friendly water treatment technologies. Among these, persulfate advanced oxidation technologies (AOPs) have attracted widespread attention due to their unique advantages. Persulfate, as a commonly used oxidant, possesses a certain oxidizing capacity, but its redox potential is relatively low, making it difficult to directly and efficiently degrade recalcitrant organic pollutants such as atrazine. However, by activating persulfate, more potent sulfate radicals (・SO4⁻) can be generated, thereby significantly improving the degradation efficiency of organic pollutants. Commonly used persulfate activation methods include thermal activation, photoactivation, and transition metal ion activation. Among these, transition metal catalytic activation has become a hot research area due to its advantages of requiring no additional energy input and being easy to operate.

[0005] Copper-based catalysts are considered among the most effective heterogeneous catalysts for activating persulfate. However, existing copper-based catalysts still suffer from significant problems during use: on the one hand, copper ions readily dissolve during the reaction, leading to decreased activity and secondary pollution; on the other hand, the materials exhibit poor structural stability, limiting their reusability and severely restricting their application in practical water treatment projects. Therefore, developing copper-based catalytic materials that combine high catalytic activity, low metal dissolution rate, and excellent structural stability has become a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0006] This invention provides a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water, its preparation method, and its application. This catalyst exhibits excellent catalytic activity in the catalytic activation of persulfate degradation in wastewater, achieving not only efficient degradation of organic pollutants but also the ability to specifically break carbon-chlorine bonds. This effectively solves the technical problems of high metal ion dissolution rate and poor structural stability in existing copper-based catalysts.

[0007] A method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water includes the following steps: (1) Dissolve nano-oxide materials and carbon source in solvent, stir thoroughly, centrifuge and dry, then calcine the obtained powder at high temperature, cool and etch with etching solution, centrifuge and dry to obtain spatially confined carbon spheres. (2) After dispersing the spatially confined carbon spheres obtained in step (1) with copper salt and precipitant in water, centrifuge and dry them, then calcine the obtained powder at high temperature and cool it to obtain the spatially confined copper-based catalyst.

[0008] The specific process conditions for each step in the above preparation route are as follows: (a) In step (1): The nano-oxide material is at least one selected from nano-magnesium oxide, nano-zinc oxide, nano-magnesium hydroxide, and nano-zinc hydroxide; the carbon source is at least one selected from resorcinol, hydroquinone, catechol, and phloroglucinol; and the solvent is at least one selected from deionized water, formaldehyde, ammonia, ethanol, methanol, and ethylene glycol. Preferably, the nano-oxide material is nano-magnesium oxide, the carbon source is resorcinol, and the solvent is formaldehyde, ammonia, or ethanol.

[0009] The concentrations of the nano-oxide material and the carbon source are 0.1-0.3 mol / L, 0.05-1.5 mol / L, 0.2-1 mol / L, 0.1-0.3 mol / L, and 2-4 mol / L, respectively. Preferably, the concentrations are 0.12 mol / L, 0.09 mol / L, 0.33 mol / L, 0.16 mol / L, and 4.28 mol / L, respectively.

[0010] The high-temperature calcination temperature is 600-1000 ℃, and the calcination time is 1-5 h. Preferably, the calcination temperature is 800 ℃, and the calcination time is 2 h.

[0011] The etching solution is at least one selected from hydrochloric acid, sodium hydroxide, and nitric acid. Preferably, the etching solution is hydrochloric acid.

[0012] The etching solution concentration is 5-20%. Preferably, the etching solution concentration is 10%.

[0013] (ii) In step (2): The copper salt is one or more selected from copper chloride, copper nitrate, and copper sulfate; the precipitant is one or more selected from sodium carbonate, potassium carbonate, and ammonium carbonate. Preferably, the copper salt is copper nitrate, and the precipitant is sodium carbonate.

[0014] The amount of the spatially confined carbon spheres is 0.3-1 mol / L, the amount of copper salt is 0.01-0.2 mol / L, and the amount of precipitant is 0.05-0.3 mol / L. Preferably, 0.5 mol / L spatially confined carbon spheres, 0.03 mol / L copper nitrate, and 0.1 mol / L sodium carbonate are dissolved in 50 ml of deionized water.

[0015] The high-temperature calcination temperature is 200-600 ℃, and the calcination time is 1-6 h. Preferably, the high-temperature calcination temperature is 400 ℃, and the calcination time is 4 h.

[0016] This invention also includes an application of the prepared spatially confined copper-based catalyst to activate persulfate for the degradation of organic pollutants in water. Specifically, it includes the following steps: adding the spatially confined copper-based catalyst to wastewater containing organic pollutants; after the catalyst is completely dispersed, adding a persulfate oxidant and continuously stirring; this catalyst can efficiently activate persulfate to produce active species, thereby rapidly degrading organic pollutants in the water. The organic pollutants include, but are not limited to, one or more of atrazine, ofloxacin, florfenicol, and tetracycline; the pH of the wastewater is 3-10; and the concentration of the organic pollutants is 1-100 mg / L.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: (1) By constructing a carbon sphere-supported CuO catalyst with spatial confinement effect, the present invention forms a local enrichment microenvironment inside the catalyst, which not only increases the collision probability of pollutants and persulfate near the active site, but also optimizes the generation pathway of reactive oxygen species, realizing the effective regulation from traditional free radical oxidation to non-free radical oxidation. With singlet oxygen (¹O2) as the dominant active species, the selectivity of the catalytic reaction and the ability to resist interference from background ions in water are improved.

[0018] (2) This invention utilizes the interfacial coupling between CuO and the conductive carbon skeleton to promote rapid electron migration and efficient Cu²⁺ / Cu⁺ cycling, thereby enhancing the ability to activate persulfate and further improving the continuous generation efficiency of reactive oxygen species, thus enabling the catalyst to have higher catalytic activity and faster pollutant removal rate.

[0019] (3) The preparation process adopted in this invention is simple, reproducible and low cost. The catalyst prepared has good structural stability, recycling performance and anti-deactivation ability, and has broad application prospects in the field of complex water pollution control and actual wastewater treatment. Attached Figure Description

[0020] Figure 1 Transmission electron microscopy image of a spatially confined copper-based catalyst (abbreviated as CuO / HCS); Figure 2 The XPS full spectrum of CuO / HCS; Figure 3 XRD patterns of spatially confined carbon spheres (abbreviated as HCS), CuO / HCS, and CuO; Figure 4 Degradation curves of atrazine in CuO / HCS, CuO / HCS-1, CuO / HCS-2, HCS-1, and CuO-1 systems; Figure 5 The degradation rate of atrazine in the CuO / HCS system under different pH conditions is shown in the graph. Figure 6 The degradation rate of atrazine in the CuO / HCS system under different PMS dosage conditions is shown in the graph. Figure 7 A cyclic experimental diagram showing the degradation of atrazine in the CuO / HCS system; Figure 8 The degradation curves of atrazine in the CuO / HCS system under different ion interferences are shown. Figure 9The graph shows the dechlorination and denitrification rates of the CuO / HCS, HCS-1, and CuO-1 systems during the degradation of atrazine. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific examples. Example 1

[0022] The preparation method of a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water according to this embodiment includes the following steps:

[0023] (1) Dissolve 0.12 mol / L nano-magnesium oxide, 0.09 mol / L resorcinol, 0.33 mol / L formaldehyde, and 0.16 mol / L ammonia in 60 mL of deionized water, then add 4.28 mol / L ethanol, stir thoroughly, centrifuge, and dry at 60 °C. Then place the resulting powder in a tube furnace and calcine at 800 °C for 2 h to obtain carbon spheres. Place the obtained carbon spheres in 10% hydrochloric acid, sonicate for 30 min, stir for 30 min, and repeat three times to obtain etched spatially confined carbon spheres (abbreviated as HCS).

[0024] (2) Place the 0.5 mol / L spatially confined carbon spheres obtained in step (1) into 50 ml of deionized water, sonicate for 30 min, add 0.03 mol / L copper nitrate, stir thoroughly, then add 0.1 mol / L sodium carbonate, react for 30 min, centrifuge, dry at 60 ℃, then place the obtained powder in a tube furnace and calcine at 400 ℃ for 4 h to obtain a spatially confined copper-based catalyst (abbreviated as CuO / HCS).

[0025] Comparative Example 1 To facilitate performance comparison, the operation steps of Example 1 were repeated, except that only step (1) was performed and step (2) was omitted. The catalyst prepared was denoted as HCS-1.

[0026] Comparative Example 2 To facilitate performance comparison, step (1) is omitted, and only step (2) is performed. The resulting catalyst is denoted as CuO-1. Example 2

[0027] To facilitate performance comparison, the operation steps of Example 1 were repeated, except that the amount of copper nitrate added in step (2) was 0.01 mol / L, and the resulting catalyst was denoted as CuO / HCS-1.

[0028] Example 3 To facilitate performance comparison, the operation steps of Example 1 were repeated, except that the amount of copper nitrate added in step (2) was 0.05 mol / L, and the resulting catalyst was denoted as CuO / HCS-2.

[0029] Figure 1 This is a transmission electron microscope (TEM) image of the CuO / HCS prepared in Example 1. Figure 1 As you can see, a layer of CuO structure is wrapped around the carbon sphere. CuO consists of irregular particles that adhere well to the surface of the carbon.

[0030] Figure 2 The image shows the XPS spectrum of CuO / HCS prepared in Example 1. Figure 2 It can be seen that CuO / HCS is composed of C, O and Cu elements.

[0031] Figure 3 The XRD full spectra of CuO / HCS, HCS, and CuO are shown. The characteristic peaks at 32.508°, 35.543°, 38.708°, 58.264°, and 61.524° correspond to (110), (11-1), (111), (202), and (11-3) of CuO. The simultaneous detection of characteristic peaks corresponding to CuC8 and CuO in the XRD spectrum of CuO / HCS material confirms the successful synthesis of CuO / HCS material.

[0032] Application Example 1 The CuO / HCS from Example 1, HCS-1 from Comparative Example 1, CuO / HCS-1 from Example 2, CuO / HCS-2 from Example 3, and CuO-1 from Comparative Example 2 were used as heterogeneous catalysts to activate persulfate brine for the treatment of organic pollutants. Specifically, 10 mg each of CuO / HCS from Example 1, HCS-1 from Comparative Example 1, CuO / HCS-1 from Example 2, CuO / HCS-2 from Example 3, and CuO-1 from Comparative Example 2 were weighed and added to 10 mg of potassium peroxymonosulfate (PMS). The mixture was then uniformly dispersed in an aqueous solution containing 50 mL of atrazine at a concentration of 10 mg / L. The reaction was carried out at a rotation speed of 600 rpm for 15 min, with 0.5 mL samples taken every 1 min to determine the pollutant concentration.

[0033] Depend on Figure 4It can be seen that, under the conditions of Application Example 1, compared with HCS-1, the degradation efficiency of the CuO / HCS catalyst with 0.03 mol / L copper doping is significantly improved, with the degradation rate increasing from 57.1% to 91.2% within 15 min of reaction. The performance of CuO / HCS-1 catalyst with 0.01 mol / L copper doping and CuO / HCS-2 catalyst with 0.05 mol / L copper doping is slightly lower than that of CuO / HCS catalyst. This may be related to the insufficient number of active sites when the copper doping is too low, the agglomeration or decreased dispersion of copper particles when the copper doping is too high, and the excessive surface coverage hindering mass transfer and electron transfer, resulting in a decrease in the number of active sites and reaction kinetics.

[0034] Application Example 2 Repeat the steps of Example 1, except that the pH and PMS dosage are replaced as in Example 1: (1) pH is set to: 3, 4, 5, 6, 6.7, 3, 8, 9, 10; (2) PMS dosage is set to: 1, 3, 5, 7, 10 mg. The concentration of pollutants at each time point is measured.

[0035] Under the conditions of this application example, by Figure 5 It can be seen that in the CuO / HCS-mediated PMS system, pH changes from 3 to 10 have almost no effect on the degradation of atrazine in the reaction system, demonstrating that the CuO / HCS system has high reaction stability and a wide applicable pH range, which is beneficial for its application in practical engineering. Figure 6 It can be seen that the degradation efficiency of atrazine by CuO / HCS increases with the increase of PMS dosage.

[0036] Application Example 3 The CuO / HCS catalyst from Example 1 was used to treat water with atrazine, and its reusability was tested. Specifically, 10 mg of the CuO / HCS catalyst from Example 1 was weighed, and 10 mg of potassium peroxymonosulfate was added. The mixture was then uniformly dispersed in an aqueous solution containing 50 mL of atrazine at a concentration of 10 mg / L. The reaction was carried out at a rotation speed of 600 rpm for 15 min, with 0.5 mL samples taken every 1 min to determine the concentration of pollutants. The reacted catalyst was then centrifuged, washed, and dried. This process was repeated five times.

[0037] Under the conditions of this application example, by Figure 7 It can be seen that after 5 cycles of testing, the CuO / HCS-mediated PMS system still showed satisfactory performance in the degradation of atrazine, indicating that it has good reusability.

[0038] Application Example 4 Repeat the steps of Example 1, except that a certain amount of Cl is added each time. - HCO3- CO3 2- NO3 - Humic acid (HA) causes Cl in the solution to... - HCO3 - CO3 2- NO3 - The concentrations of pollutants were all 10 mM, and the concentration of humic acid was 2 mg / L. The concentrations of pollutants at each time point were measured.

[0039] Under the conditions of this embodiment, by Figure 8 It can be seen that the changes in inorganic ions have almost no effect on the degradation of atrazine in the reaction system, which proves that the CuO / HCS system has a high anti-interference ability.

[0040] Application Example 5 The CuO / HCS catalyst from Example 1 was used to degrade atrazine in water, and the chloride and nitrogen ions in the resulting liquid were determined by ion chromatography. Specifically, 10 mg of the CuO / HCS catalyst from Example 1 was weighed, and 10 mg of potassium persulfate was added. The mixture was then uniformly dispersed in 50 mL of an aqueous solution of atrazine with a concentration of 10 mg / L. The reaction was carried out at a speed of 600 rpm for 15 min. After 15 min, 1 mL of the solution was extracted, filtered, and the concentrations of chloride and nitrogen ions were determined by ion chromatography.

[0041] Under the conditions of this embodiment, by Figure 9 It can be seen that the CuO / HCS catalyst has a dechlorination rate of 46.39% and a denitrification rate of 66.12% during the degradation of atrazine, which proves that the CuO / HCS system has the ability to specifically break carbon-chlorine bonds and has a high degradation capacity for atrazine.

[0042] Example 4 To facilitate performance comparison, the operation steps of Example 1 are repeated, except that in step (1), the high-temperature calcination temperature is 600 ℃.

[0043] The CuO / HCS material prepared under the conditions of this embodiment has inferior performance to the material prepared under the conditions of Example 1. Under the same conditions as Application Example 1, the degradation rate of atrazine pollutant was 63.7% within 15 min of the reaction.

[0044] Example 5 To facilitate performance comparison, the operation steps of Example 1 were repeated, except that in step (1), the etching solution concentration was 5%.

[0045] The CuO / HCS material prepared under the conditions of this embodiment has inferior performance to the material prepared under the conditions of Example 1. Under the same conditions as Application Example 1, the degradation rate of atrazine pollutant was 70.4% within 15 min of reaction.

[0046] Example 6 To facilitate performance comparison, the operation steps of Example 1 are repeated, except that in step (2), the high-temperature calcination temperature is 300 ℃.

[0047] The CuO / HCS material prepared under the conditions of this embodiment has inferior performance to the material prepared under the conditions of Example 1. Under the same conditions as Application Example 1, the degradation rate of atrazine pollutant was 82.7% within 15 min of the reaction.

[0048] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water, characterized in that, Includes the following steps: (1) Dissolve nano-oxide materials and carbon source in solvent, stir thoroughly, centrifuge and dry, then calcine the obtained powder at high temperature, cool and etch with etching solution, centrifuge and dry to obtain spatially confined carbon spheres. (2) After dispersing the spatially confined carbon spheres obtained in step (1) with copper salt and precipitant in water, centrifuge and dry them, then calcine the obtained powder at high temperature and cool it to obtain the spatially confined copper-based catalyst.

2. The method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water according to claim 1, characterized in that, In step (1), the nano-oxide material is at least one of nano-magnesium oxide, nano-zinc oxide, nano-magnesium hydroxide, and nano-zinc hydroxide; the carbon source is at least one of resorcinol, hydroquinone, catechol, and phloroglucinol; the solvent is at least one of deionized water, formaldehyde, ammonia, ethanol, methanol, and ethylene glycol; and the etching solution is at least one of hydrochloric acid, sodium hydroxide, and nitric acid.

3. The method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water according to claim 1, characterized in that, In step (1), the concentration of the nano-oxide material is 0.1-0.3 mol / L, the concentration of the carbon source is 0.05-1.5 mol / L, the concentration of formaldehyde is 0.2-1 mol / L, the concentration of ammonia is 0.1-0.3 mol / L, and the concentration of ethanol is 2-4 mol / L; the concentration of the etching solution is 5-20%.

4. The method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water according to claim 1, characterized in that, In step (1), the high-temperature calcination temperature is 600-1000 ℃ and the calcination time is 1-5 h.

5. The method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water according to claim 1, characterized in that, In step (2), the copper salt is one or more of copper chloride, copper nitrate, and copper sulfate; the precipitant is one or more of sodium carbonate, potassium carbonate, and ammonium carbonate.

6. The method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water according to claim 1, characterized in that, In step (2), the amount of the spatially confined carbon spheres is 0.3-1 mol / L, the amount of copper salt is 0.01-0.2 mol / L, and the amount of precipitant is 0.05-0.3 mol / L.

7. The method for preparing a spatially confined copper-based catalyst for activating persulfate degradation of organic pollutants in water according to claim 1, characterized in that, In step (2), the high-temperature calcination temperature is 200-600 ℃ and the calcination time is 1-6 h.

8. A spatially confined copper-based catalyst prepared by the method according to any one of claims 1 to 7, characterized in that, The catalyst has the ability to activate persulfate to degrade organic pollutants in water.

9. The application of the spatially confined copper-based catalyst as described in claim 8 in the activation of persulfate degradation of organic pollutants in water, characterized in that, Includes the following steps: Add the spatially confined copper-based catalyst of claim 8 to wastewater containing organic pollutants, and after the catalyst is completely dispersed, add persulfate oxidant and continue stirring. The catalyst can efficiently activate persulfate to generate active species, thereby rapidly degrading organic pollutants in the water.

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