A method for treating organic wastewater using a heterojunction activated oxidant formed by carbon nitride and copper nitride.

Abstract

This invention provides a method for treating organic wastewater using a heterojunction activated oxidant formed by carbon nitride and copper nitride, comprising the following steps: S1, blending Cu(CH3COO)2·H2O, C2H4N4, and B2O3 to obtain precursor A; S2, pyrolyzing precursor A to purify it into a heterojunction Cu3N / g-C3N4; S3, adding the heterojunction Cu3N / g-C3N4 and an oxidant to wastewater containing organic pollutants to carry out a wastewater treatment reaction. This invention utilizes the interfacial micro-electric field formed by the electron shift due to the Fermi level difference between g-C3N4 and Cu3N, mediating the superexchange interaction of electron cycling between pollutants, catalyst, and oxidant (H2O2), promoting the catalytic reduction of H2O2, and improving the effective utilization rate of the oxidant. This invention features a simple process, convenient operation, mild conditions, and good treatment effect, making it suitable for the treatment of various types of organic wastewater.

Description

Technical Field

[0001] This invention relates to the field of water pollution control technology, and in particular to a method for treating organic wastewater by activating an oxidant using a heterojunction formed by carbon nitride and copper nitride. Background Technology

[0002] With increasing industrialization, various organic pollutants and anthropogenic chemicals have entered aquatic environments through different pathways, triggering a serious freshwater crisis. Bisphenol A (BPA) is widely used in plastic production and poses a significant threat to water bodies. It is a new type of pollution and is on the monitoring lists of many countries and regions. Studies have shown that BPA is an endocrine disruptor, which not only harms aquatic environments but may also damage the reproductive system and affect the health of newborns due to its accumulation in the human body. However, traditional wastewater treatment technologies cannot effectively remove BPA from water bodies.

[0003] In the field of water treatment, the Fenton process has attracted considerable attention. In a typical homogeneous Fenton process, hydroxyl radicals are generated from hydrogen peroxide catalyzed by ferrous ions. The resulting ferric ions can then react with hydrogen peroxide to produce ferrous ions. During the reaction, the hydroxyl radicals attack pollutants, and through a chain reaction, organic pollutants are continuously mineralized into low-toxicity or even non-toxic small molecule products. However, the traditional homogeneous Fenton process still has some drawbacks, such as the need to control the reaction pH range, the easy generation of large amounts of iron sludge, and low hydrogen peroxide utilization efficiency, which limit its application. Therefore, developing a novel heterogeneous catalyst for the efficient activation of hydrogen peroxide is an urgent need and a challenge in the field of water treatment. Recent studies have revealed that transition metal catalysts (Fe, Mn, Cu, etc.) generally have better catalytic activity than other technologies, and are therefore favored by researchers. Among them, Cu-based catalysts are more suitable for activating hydrogen peroxide than other transition metal catalysts due to their ability to regulate morphology and grain boundaries and their moderate H2O2 binding energy. Compared with copper-based oxides, Cu3N has an anti-ReO3 cubic structure and is an electrochemically stable copper-based compound. Furthermore, its Cu is in a low valence state and has an electron-rich density that can catalyze the reduction of H2O2. Therefore, Cu3N is expected to become a highly efficient and stable Fenton reaction catalyst, but Cu3N has not yet been used in the field of Fenton reaction.

[0004] Studies have shown that the Fenton reaction depends on the metal valence state cycle; as Haber-Weiss described, the metal generates a considerable amount of ·OH by sacrificing electrons. However, maintaining the continuous generation of ·OH after the metal valence state change remains a significant challenge, and no method has yet been found to overcome this limitation. Common methods involve adding additional light, electricity, or organic molecules to sustain ·OH generation. Therefore, a continuous electronic equilibrium state is crucial for efficient ·OH generation. Combining two materials with different electronic states may create an interfacial micro-electric field between the interfaces. This micro-electric field can promote electron interactions, making the electron cycle of Cu3N more efficient, thereby continuously catalyzing the generation of ·OH from H2O2. However, there are currently no reported studies on Cu3N-based composite catalysts.

[0005] Based on these considerations, we have for the first time constructed a Cu3N / g-C3N4 with an interfacial micro-electric field using work function difference. Experiments and theoretical calculations confirmed the formation and effect of the interfacial micro-electric field, which promotes the superexchange interaction of electron transfer between BPA-catalyst-H2O2. This may be the reason why Cu3N / g-C3N4 exhibits superior activity compared to Cu3N alone. Simultaneously, this interaction improves the electronic structure of Cu3N through pd orbital hybridization, facilitating electron transitions and H2O2 adsorption, thereby enhancing the effective utilization rate of the oxidant. To date, the application of heterojunctions formed by carbon nitride and copper nitride in water treatment has not been reported in the literature or patents. In conclusion, there is an urgent need to develop a new technical solution to address the problems existing in current technologies. Summary of the Invention

[0006] Based on this, the present invention provides a method for treating organic wastewater by activating an oxidant using a heterojunction formed by carbon nitride and copper nitride. The main purpose of this method is to address the problem that existing research has limited application of copper nitrides in water treatment, leading to insufficient understanding of their performance and poor catalytic activity against H2O2. This method has advantages such as simple process, mild conditions, ease of control, wide adaptability to wastewater pH, and good treatment effect.

[0007] One object of the present invention is to provide a method for treating organic wastewater by activating an oxidant using a heterojunction formed by carbon nitride and copper nitride, comprising the following steps:

[0008] S1. Cu(CH3COO)2·H2O, C2H4N4 and B2O3 are blended to obtain precursor A;

[0009] S2. Pyrolyze the precursor A and purify it to obtain heterojunction Cu3N / g-C3N4;

[0010] S3. Add the heterojunction Cu3N / g-C3N4 and oxidant to the wastewater containing organic pollutants to carry out the wastewater treatment reaction.

[0011] Furthermore, the oxidant is H2O2.

[0012] Further, in step S1, the mass ratio of Cu(CH3COO)2·H2O, C2H4N4 and B2O3 is (0.5-4):5:10.

[0013] Further, in step S2, the pyrolysis is performed by heating to 400-600°C at a heating rate of 3-8°C / min.

[0014] Furthermore, in step S2, the pyrolysis time is 1-3 hours.

[0015] Further, in step S3, the molar concentration ratio of the heterojunction Cu3N / g-C3N4 to the organic pollutant is 10-100:1.

[0016] Further, in step S3, the mass concentration ratio of the oxidant to the organic pollutant is 10-40:1.

[0017] Furthermore, in step S3, the initial pH value of the wastewater containing organic pollutants is 3-11.

[0018] Furthermore, in step S3, the wastewater treatment reaction time is 10-30 min.

[0019] The present invention has the following beneficial effects:

[0020] This invention provides a method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant. This method utilizes an interfacial micro-electric field, created by the electron shift due to the Fermi level difference between g-C3N4 and Cu3N, to mediate a superexchange interaction of electron cycling between pollutants, catalysts, and oxidants (H2O2). Through the π-π interaction between g-C3N4 and bisphenol A (BPA), electrons are absorbed and directionally transferred to Cu3N sites, promoting the catalytic reduction of H2O2. Furthermore, the interfacial micro-electric field improves the surface electron distribution, resulting in higher Cu3N / g-C3N4 activity compared to g-C3N4 and Cu3N alone. Simultaneously, pd orbital hybridization enhances electron transition activity, and the d-band center shifts to higher energy levels, strengthening H2O2 adsorption and reaction. This interfacial micro-electric field-mediated superexchange interaction significantly improves the effective utilization rate of H2O2, increasing the reaction kinetic constant by 9.4 times (from 0.01561 min). -1 Increased to 0.147 min -1In this process, reactive oxygen species, primarily ·OH, break bonds and open rings of BPA through electrophilic addition reactions, ultimately degrading it into low-toxicity and non-toxic small molecule products. This invention provides a method for finely controlling the electronic structure of catalysts and the electron cycle of the Fenton reaction, which is expected to offer new ideas for efficient, sustainable, and low-carbon Fenton reactions.

[0021] The heterojunction Cu3N / g-C3N4 surface Cu active site potential of the present invention is more correct, the catalyst has good structure and function, strong activity, can activate hydrogen peroxide, generate a large amount of ·OH through the free radical pathway, and has high oxidant utilization efficiency and pollutant removal efficiency.

[0022] The method for generating free radicals using a heterojunction Cu3N / g-C3N4 activating oxidant, employed in this invention, demonstrates excellent effectiveness in treating bisphenol A (BPA) wastewater with an initial pH range of 3-11. This indicates that the method has a wide pH adaptability range for wastewater, avoiding the cost of pre-adjusting the wastewater pH to acidity. The method for treating organic wastewater using a heterojunction activating oxidant formed from carbon nitride and copper nitride, provided by this invention, is simple, easy to operate, operates under mild conditions, and achieves good treatment results, making it suitable for treating various types of organic wastewater. Attached Figure Description

[0023] Figure 1 The image shows a transmission electron microscope (HR-TEM) image of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1.

[0024] Figure 2 The X-ray diffraction (XRD) pattern of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1 is shown.

[0025] Figure 3 The photoelectron spectrum (XPS) of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1 is shown.

[0026] in,

[0027] Figure 3 (a) shows the Cu2p orbital spectrum of the heterojunction Cu3N / g-C3N4-3;

[0028] Figure 3 (b) shows the Cu2p orbital spectrum of the heterojunction Cu3N / g-C3N4-3 after the reaction with H2O2 and BPA;

[0029] Figure 4 The electron paramagnetic resonance (EPR) spectrum of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1 is shown in comparison with Cu3N.

[0030] Figure 5The DFT calculation results of the heterojunctions Cu3N / g-C3N4-3, Cu3N, and g-C3N4 prepared in Example 1 are shown.

[0031] in,

[0032] Figure 5 (a) shows the electron density distribution at the interface of the heterojunction Cu3N / g-C3N4-3;

[0033] Figure 5 (b) shows the partial density of states plot of g-C3N4;

[0034] Figure 5 (c) shows the partial density of states plot of Cu3N; Figure 5 (d) shows the partial density of states diagram of Cu3N / g-C3N4-3. Detailed Implementation

[0035] 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.

[0036] 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.

[0037] Considering that bisphenol A (BPA) pollutants are frequently used as plasticizers in industry, 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 plastics 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 in organisms lead to the widespread spread of drug-resistant bacteria and genes, causing irreversible damage to the reproductive, nervous, and endocrine systems of mammals (such as hormonal imbalances and reproductive system effects), directly threatening human health. Therefore, this invention selects bisphenol A (BPA), the most frequently detected bisphenol pollutant in industrial wastewater in my country, as the target pollutant. Simulated BPA wastewater is used as the wastewater to be treated, and the degree of BPA degradation represents the treatment efficiency of the organic wastewater.

[0038] The chemical reagents used in the embodiments, comparative examples and test examples of this invention, such as copper acetate monohydrate (Cu(CH3COO)2·H2O), dicyandiamide (C2H4N4), boron trioxide (B2O3), H2O2, and BPA, are all of analytical grade.

[0039] Unless otherwise specified, the concentration of H2O2 in the reaction solutions of the embodiments and comparative examples of this invention is 50 mg / L.

[0040] The water used in the embodiments, comparative examples and test examples of this invention is deionized water.

[0041] The method for detecting the residual BPA concentration in the embodiments, comparative examples, and test examples of this invention is as follows: liquid chromatography model: Shimadzu LC-16; mobile phase A is methanol, mobile phase B is ultrapure water, A:B=0.3:0.7; flow rate: 1 mL / min; column temperature: 30℃; detection wavelength: 280 nm; column: C18 (150 mm × 4.6 mm, 5 μm).

[0042] In the Cu3N / g-C3N4-x examples and test cases of this invention, x represents the Cu content, and its value is the same as the mass (unit: g) of Cu(CH3COO)2·H2O.

[0043] Example 1

[0044] A method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant includes the following steps:

[0045] S1. Grind and mix 3 g of Cu(CH3COO)2·H2O, 5 g of C2H4N4 and 10 g of B2O3 in an agate mortar to obtain precursor A.

[0046] S2. Place the precursor A in a 50 mL corundum crucible, place the crucible in a muffle furnace, and heat it to 500 °C at a heating rate of 5 °C / min for 2 h. Wash the product with oxygen-free water to remove impurities and boron, and dry it to obtain a heterojunction Cu3N / g-C3N4-3;

[0047] S3. Add 25 mg of Cu3N / g-C3N4-3 to 50 mL of wastewater with an initial pH of 7 and a BPA concentration of 5 mg / L. Add H2O2 until the concentration in the solution is 50 mg / L. Stir the solution at 25℃ and 500 rpm for 20 min to treat the wastewater.

[0048] Since Cu3N / g-C3N4-3 has the best activity, it was selected as the model catalyst. In the following text, CAT also represents Cu3N / g-C3N4-3.

[0049] Figure 1 The image shows a transmission electron microscope (HR-TEM) image of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1.

[0050] Figure 2 The X-ray diffraction (XRD) pattern of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1 is shown.

[0051] Figure 3 The photoelectron spectrum (XPS) of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1 is shown.

[0052] in, Figure 3 (a) shows the Cu2p orbital spectrum of the heterojunction Cu3N / g-C3N4-3;

[0053] Figure 3 (b) shows the Cu2p orbital spectrum of the heterojunction Cu3N / g-C3N4-3 after the reaction with H2O2 and BPA;

[0054] Figure 4 The electron paramagnetic resonance (EPR) spectrum of the heterojunction Cu3N / g-C3N4-3 prepared in Example 1 is shown in comparison with Cu3N.

[0055] Figure 5 The DFT calculation results of the heterojunctions Cu3N / g-C3N4-3, Cu3N, and g-C3N4 prepared in Example 1 are shown.

[0056] in,

[0057] Figure 5 (a) shows the electron density distribution at the interface of the heterojunction Cu3N / g-C3N4-3;

[0058] Figure 5 (b) shows the partial density of states plot of g-C3N4;

[0059] Figure 5 (c) shows the partial density of states plot of Cu3N;

[0060] Figure 5 (d) shows the partial density of states diagram of Cu3N / g-C3N4-3.

[0061] Example 2

[0062] A method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant includes the following steps:

[0063] S1. Grind and mix 0.5 g of Cu(CH3COO)2·H2O, 5 g of C2H4N4 and 10 g of B2O3 in an agate mortar to obtain precursor A.

[0064] S2. Place the precursor A in a 50 mL corundum crucible, place the crucible in a muffle furnace, and heat it to 500 °C at a heating rate of 5 °C / min for 2 h. Wash the product with oxygen-free water to remove impurities and boron, and dry it to obtain a heterojunction Cu3N / g-C3N4-0.5;

[0065] S3. Add 25 mg of Cu3N / g-C3N4-0.5 to 50 mL of wastewater with an initial pH of 7 and a BPA concentration of 5 mg / L. Add H2O2 until the concentration in the solution is 50 mg / L. Stir the solution at 25℃ and 500 rpm for 20 min to treat the wastewater.

[0066] Example 3

[0067] A method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant includes the following steps:

[0068] S1. Grind and mix 1 g of Cu(CH3COO)2·H2O, 5 g of C2H4N4 and 10 g of B2O3 in an agate mortar to obtain precursor A.

[0069] S2. Place the precursor A in a 50 mL corundum crucible, place the crucible in a muffle furnace, and heat it to 500 °C at a heating rate of 5 °C / min for 2 h. Wash the product with oxygen-free water to remove impurities and boron, and dry it to obtain a heterojunction Cu3N / g-C3N4-1;

[0070] S3. Add 25 mg of Cu3N / g-C3N4-1 to 50 mL of wastewater with an initial pH of 7 and a BPA concentration of 5 mg / L. Add H2O2 until the concentration in the solution is 50 mg / L. Stir the solution at 25℃ and 500 rpm for 20 min to carry out the wastewater treatment reaction.

[0071] Example 4

[0072] A method for treating organic wastewater by activating an oxidant using a heterojunction formed by carbon nitride and copper nitride includes the following steps: S1, grinding and mixing 2 g of Cu(CH3COO)2·H2O, 5 g of C2H4N4 and 10 g of B2O3 in an agate mortar to obtain precursor A;

[0073] S2. Place the precursor A in a 50 mL corundum crucible, place the crucible in a muffle furnace, and heat it to 500 °C at a heating rate of 5 °C / min for 2 h. Wash the product with oxygen-free water to remove impurities and boron, and dry it to obtain a heterojunction Cu3N / g-C3N4-2;

[0074] S3. Add 25 mg of Cu3N / g-C3N4-2 to 50 mL of wastewater with an initial pH of 7 and a BPA concentration of 5 mg / L. Add H2O2 until the concentration in the solution is 50 mg / L. Stir the solution at 25℃ and 500 rpm for 20 min to treat the wastewater.

[0075] Example 5

[0076] A method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant includes the following steps:

[0077] S1. Grind and mix 4 g of Cu(CH3COO)2·H2O, 5 g of C2H4N4 and 10 g of B2O3 in an agate mortar to obtain precursor A.

[0078] S2. Place the precursor A in a 50 mL corundum crucible, place the crucible in a muffle furnace, and heat it to 500 °C at a heating rate of 5 °C / min for 2 h. Wash the product with oxygen-free water to remove impurities and boron, and dry it to obtain a heterojunction Cu3N / g-C3N4-4;

[0079] S3. Add 25 mg of Cu3N / g-C3N4-4 to 50 mL of wastewater with an initial pH of 7 and a BPA concentration of 5 mg / L. Add H2O2 until the concentration in the solution is 50 mg / L. Stir the solution at 25℃ and 500 rpm for 20 min to treat the wastewater.

[0080] Comparative Example

[0081] A method for treating organic wastewater using a heterojunction activated oxidant formed by carbon nitride and copper nitride is disclosed. The difference between this comparative example and Example 1 is that Cu(CH3COO)2·H2O is not added; all other components and treatment methods are the same as in Example 1. This comparative example prepares g-C3N4.

[0082] Test Example 1

[0083] Test method:

[0084] The Cu3N / g-C3N4-x prepared in Examples 1-5 and the g-C3N4 prepared in the comparative example were used as catalysts, and H2O2 was used as the oxidant. Simulated organic wastewater with an initial BPA concentration of 5 mg / L was prepared without adjusting the pH of the wastewater.

[0085] Seven 100 mL beakers were used as reaction vessels. 50 mL of 5 mg / L BPA wastewater was added to each vessel, creating seven treatment groups. 25 mg of Cu3N / g-C3N4-x with varying Cu content was added to each group, and H2O2 was added to the reaction solution to a concentration of 50 mg / L. Specifically: Treatment Group 1: Cu3N / g-C3N4-0.5 prepared in Example 2; Treatment Group 2: Cu3N / g-C3N4-1 prepared in Example 3; Treatment Group 3: Cu3N / g-C3N4-2 prepared in Example 4; Treatment Group 4: Cu3N / g-C3N4-3 prepared in Example 1; Treatment Group 5: Cu3N / g-C3N4-4 prepared in Example 5; Treatment Group 6: g-C3N4 prepared in the comparative example; Example 7: No catalyst, only H2O2. Under conditions of 25℃ and 500 rpm, samples were taken and the residual BPA concentration was measured at 0, 2, 5, 10, and 20 min of reaction, and the BPA removal rate was calculated. The test results are shown in Table 1.

[0086] Table 1. Test results of BPA wastewater treated with Cu3N / g-C3N4-x at different Cu contents.

[0087]

[0088] Test results showed that neither g-C3N4 nor H2O2 alone could effectively remove BPA from wastewater. The removal rate of BPA increased with the increase of Cu content. When using Cu3N / g-C3N4-3 prepared in Example 1, the degradation rate reached its highest level (94.30%) after 20 min of reaction. However, the BPA removal rate decreased with further increase of Cu content, indicating that Cu3N / g-C3N4-3 had the best activity effect. The ·OH generated by its activation of H2O2 enabled the rapid and effective degradation of pollutant BPA.

[0089] Test Example 2

[0090] Test method: Cu3N / g-C3N4-3 prepared in Example 1 was used as the catalyst, and H2O2 was used as the oxidant. Simulated organic wastewater with an initial BPA concentration of 5 mg / L was prepared without adjusting the pH of the wastewater.

[0091] Four 100 mL beakers were used as reaction vessels. 50 mL of 5 mg / L BPA wastewater was added to each vessel, creating four treatment groups. Different masses of Cu3N / g-C3N4-3 were added to each group: Treatment Group 1: 15 mg Cu3N / g-C3N4-3; Treatment Group 2: 20 mg Cu3N / g-C3N4-3; Treatment Group 3: 25 mg Cu3N / g-C3N4-3; Treatment Group 4: 50 mg Cu3N / g-C3N4-3. Under conditions of 25℃ and 500 rpm, the mixture was thoroughly stirred on a magnetic stirrer. H2O2 was then added until the reaction solution concentration reached 50 mg / L. Samples were taken at 0, 2, 5, 10, and 20 min to determine the residual BPA concentration, and the BPA removal rate was calculated. The test results are shown in Table 2.

[0092] Table 2. Test results of BPA wastewater treated with different concentrations of Cu3N / g-C3N4-3

[0093]

[0094] The test results show that the dosage of Cu3N / g-C3N4-3 affects the efficiency of activated H2O2 oxidation and degradation of BPA in simulated wastewater. Within a certain range, the BPA degradation rate increases with the increase of Cu3N / g-C3N4-3 dosage. When the Cu3N / g-C3N4-3 dosage is 0.3 g / L, the BPA removal rate reaches 66.78% after 20 min of reaction. When the dosage is increased to 0.5 g / L, the BPA removal rate increases to 92.96% after the same reaction time. However, when the dosage is further increased to 1.0 g / L, the BPA removal rate decreases by 19% after the same reaction time. This indicates that under these reaction conditions, an excess of Cu3N / g-C3N4-3 in the solution affects the mass transfer process of BPA and even the active species in the solution, thus reducing the removal rate of BPA throughout the reaction process. The above results indicate that the rate and extent of the oxidative degradation reaction of the target pollutant can be controlled by adjusting the dosage of Cu3N / g-C3N4. In practical applications, the dosage of Cu3N / g-C3N4 can be selected based on the initial pollutant concentration in the wastewater and the required wastewater treatment efficiency, in order to maximize material savings and reduce treatment costs.

[0095] Test Example 3

[0096] Test method: Cu3N / g-C3N4-3 prepared in Example 1 was used as the catalyst, and H2O2 was used as the oxidant. Simulated organic wastewater with an initial BPA concentration of 5 mg / L was prepared without adjusting the pH of the wastewater.

[0097] Five 100 mL beakers were used as reaction vessels. 50 mL of 5 mg / L BPA wastewater was added to each vessel, creating five treatment groups. 25 mg of Cu3N / g-C3N4-3 and different concentrations of H2O2 were added to each group: Treatment Group 1: 50 mg / L H2O2; Treatment Group 2: 80 mg / L H2O2; Treatment Group 3: 100 mg / L H2O2; Treatment Group 4: 150 mg / L H2O2; Treatment Group 5: 200 mg / L H2O2. The wastewater treatment reaction was carried out under conditions of 25℃ and 500 rpm using a magnetic stirrer. Samples were taken at 0, 2, 5, 10, and 20 min to determine the residual BPA concentration, and the BPA removal rate was calculated. The test results are shown in Table 3.

[0098] Table 3. Test results of BPA wastewater treated with different concentrations of H2O2

[0099]

[0100] Test results show that the dosage of H2O2 affects the efficiency of the system in oxidizing and degrading simulated BPA wastewater. As the dosage of H2O2 increases, the degradation rate of BPA decreases. When the dosage of H2O2 is 50 mg / L, a removal rate of 92.68% of BPA can be achieved after 20 minutes of reaction. However, when the dosage of H2O2 is further increased, the removal rate of BPA decreases after the same reaction time, indicating that H2O2 is in excess. Excess H2O2 does not significantly accelerate the reaction process, resulting in waste of oxidant and reduced efficiency in oxidizing BPA. These results also demonstrate that the Cu3N / g-C3N4 catalyst provided by this invention exhibits good structure-activity relationship, high H2O2 decomposition efficiency, and high utilization rate, avoiding the problems of H2O2 waste and secondary pollution caused by the poor structure-activity relationship of traditional H2O2 catalysts. When treating actual wastewater, the dosage of H2O2 should be selected according to the initial pollutant concentration and treatment efficiency requirements to save reactants and reduce treatment costs.

[0101] Test Example 4

[0102] Test method: Using Cu3N / g-C3N4-3 prepared in Example 1 as the catalyst and H2O2 as the oxidant, simulated organic wastewater with an initial BPA concentration of 5 mg / L was prepared.

[0103] Five 100 mL beakers were used as reaction vessels. 50 mL of 5 mg / L BPA wastewater was added to each vessel, creating five treatment groups: Treatment Group 1: Initial pH of BPA wastewater adjusted to 3; Treatment Group 2: Initial pH of BPA wastewater adjusted to 5; Treatment Group 3: Initial pH of BPA wastewater adjusted to 7; Treatment Group 4: Initial pH of BPA wastewater adjusted to 9; Treatment Group 5: Initial pH of BPA wastewater adjusted to 11. 25 mg of Cu3N / g-C3N4-3 and H2O2 were added to each vessel until the reaction solution concentration reached 50 mg / L. The reaction was carried out at 25℃ and 500 rpm using a magnetic stirrer. Samples were taken at 0, 2, 5, 10, 15, and 20 min to determine the remaining BPA concentration, and the BPA removal rate was calculated. The test results are shown in Table 4.

[0104] Table 4. Test results of BPA wastewater treated with different initial pH values.

[0105]

[0106] Test results show that the degradation rate of pollutants does not change significantly when the pH range is 3-9, and BPA is almost completely degraded after 20 minutes of reaction. This may be because the activity of ·OH is enhanced under acidic conditions, further accelerating the reaction rate. Under alkaline conditions (pH=11), both the BPA removal rate and efficiency decrease, but the BPA removal rate can still reach 48.65% after 20 minutes of reaction, indicating that the system still has a certain oxidative degradation capacity for alkaline wastewater. Therefore, this system has a wide pH adaptability range for wastewater, but it is most effective in treating organic wastewater with an initial pH range of 3-9.

[0107] 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 its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This method of description is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the various embodiments 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 a heterojunction formed by carbon nitride and copper nitride to activate an oxidant, characterized in that, Includes the following steps: S1. Cu(CH3COO)2·H2O, C2H4N4 and B2O3 are blended to obtain precursor A; S2. Pyrolyze the precursor A and purify it to obtain heterojunction Cu3N / g-C3N4; S3. Add the heterojunction Cu3N / g-C3N4 and oxidant to the wastewater containing organic pollutants to carry out the wastewater treatment reaction.

2. The method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant, as described in claim 1, is characterized in that... The oxidant is H2O2.

3. The method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate the oxidant, as described in claim 1, is characterized in that... In step S1, the mass ratio of Cu(CH3COO)2·H2O, C2H4N4 and B2O3 is (0.5-4):5:

10.

4. The method for treating organic wastewater using a heterojunction activated by carbon nitride and copper nitride according to claim 1, characterized in that, In step S2, the pyrolysis is performed by heating to 400-600℃ at a heating rate of 3-8℃ / min.

5. The method for treating organic wastewater using a heterojunction activated by carbon nitride and copper nitride according to claim 1, characterized in that, In step S2, the pyrolysis time is 1-3 hours.

6. The method for treating organic wastewater using a heterojunction activated by carbon nitride and copper nitride according to claim 1, characterized in that, In step S3, the molar concentration ratio of the heterojunction Cu3N / g-C3N4 to the organic pollutant is 10-100:

1.

7. The method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant, as described in claim 1, is characterized in that... In step S3, the mass concentration ratio of the oxidant to the organic pollutant is 10-40:

1.

8. The method for treating organic wastewater using a heterojunction activated by carbon nitride and copper nitride according to claim 1, characterized in that, In step S3, the initial pH value of the wastewater containing organic pollutants is 3-11.

9. The method for treating organic wastewater using a heterojunction formed by carbon nitride and copper nitride to activate an oxidant, as described in claim 1, is characterized in that... In step S3, the wastewater treatment reaction time is 10-30 minutes.

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