A method for treating organic wastewater by using electron-rich spinel anode

Abstract

The application discloses a method for treating organic wastewater by using an electron-rich spinel anode, and comprises the following steps: electrolyzing the organic wastewater by using an electron-rich spinel anode, wherein the electron-rich spinel anode is an anode in which metal ions M with high electron filling degree are introduced into tetrahedral sites of Co3O4, and the metal ions M are Ni, Cu or Zn. The spinel oxide anode synthesized by the application can efficiently remove various organic pollutants, and has a lower barrier for generating ·OH. The electron-rich spinel anode system constructed by the application can realize efficient generation of ·OH, and inhibit the overoxidation of ·OH to generate O2, thereby providing a theoretical and technical basis for treating organic wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, and particularly relates to a method for treating organic wastewater. Background Technology

[0002] With industrialization and urbanization, the treatment of organic wastewater has become an increasingly important issue. Various technologies, including advanced oxidation processes, biodegradation, photocatalysis, and electrocatalysis, are used for wastewater purification. Among them, electrochemical oxidation (EO) technology has advantages such as strong oxidizing capacity, environmental friendliness, fast reaction kinetics, and modular treatment methods, making it a highly ideal technology for treating organic pollutants.

[0003] Due to the diversity of active species, there are two reaction mechanisms for pollutant degradation in electrochemical oxidation systems. One is direct oxidation mediated by slow electron transfer (e... - Compared to processes with a redox potential of 1.5V vs. RHE, indirect oxidation processes based on strong oxidizing agents (such as ·OH, redox potential: 2.8V vs. RHE) have greater application prospects in wastewater treatment. The activity of an indirect oxidation system is related to the generation efficiency of ·OH at the anode interface, which involves the oxidative dehydrogenation of H2O molecules (Equation 1). Common anode materials assembled in electrochemical oxidation systems include boron-doped diamond (BDD) and size-stable anodes (DSA, TiO2 / PbO2, TiO2 / Sb2O5-SnO2). In particular, these materials are inactive and have a high oxygen evolution reaction (OER) potential, effectively inhibiting the further oxidation of ·OH to O2 (Equation 2). However, the preparation of these anodes involves high costs and cumbersome procedures. More importantly, due to the lack of an active medium at the anode, the kinetics of H2O oxidation to ·OH are slow, which restricts the further promotion of this technology in wastewater treatment. Therefore, there is an urgent need to develop highly active anodes to efficiently generate ·OH to eliminate pollutants in wastewater.

[0004] H₂O→·OH + H₂ + +e - (1)

[0005] 2·OH→O2+2H + +2e - (2)

[0006] During H2O oxidation, the formation of ·OH is not completely separated from the OER. Anode materials with low OER onset potentials also exhibit excellent performance in ·OH formation. Spinel oxide (AB2O4) has been widely used in electrochemical oxidation systems due to its excellent electrochemical activity and tunable electronic structure. Typically, octahedral sites (B... Oh 3+ ) compared to tetrahedral sites (ATd 2+ It has more low-energy bands, thus exhibiting a higher binding energy with H2O molecules. Furthermore, A... Td 2+ and B Oh 3+ Strong electron delocalization between sites can effectively induce H2O in B Oh 3+ The site is oxidized to ·OH. Traditional spinel material B... Oh 3+ Electron orbitals at positions with low occupancy, such as Co... Oh 3+ (3d 6 , t 2g 6 e g 0 ), Fe Oh 3+ (3d 5 , t 2g 3 e g 2 Mn Oh 3+ (3d 4 , t 2g 4 e g 0 When B combines with H2O molecules, Oh 3+ The excessive hybridization between the 3d and O 2p orbitals prevents the adsorbed ·OH from detaching from the anolyte interface, leading to ·OH peroxidation into O2. Therefore, it is necessary to modify conventional spinel oxides to weaken the B... Oh 3+ The binding strength between the site and oxygen-containing substances releases adsorbed ·OH during water oxidation, thereby achieving ·OH-mediated wastewater purification in the electrocatalytic oxidation system. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for treating organic wastewater using an electron-rich spinel anode that can effectively promote the rate-limiting step of H2O oxidation to generate ·OH and strictly inhibit the further oxidation of ·OH to generate O2 and lose its oxidizing ability.

[0008] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0009] A method for treating organic wastewater using an electron-rich spinel anode includes the following steps: electrolyzing the organic wastewater using an electron-rich spinel anode, wherein the electron-rich spinel anode is a metal ion M with a high electron filling degree introduced into the tetrahedral sites of Co3O4, enabling it to effectively couple with M. Td 2+ Electron repulsion between Co and O atoms and Co Oh 3+ The π contribution between the O atom and the electron-rich Co atoms constructs an electron-rich Co. Oh 3+ Center, weaken Co Oh 3+ The binding strength between the site and oxygen-containing substances induces the oxidation and dehydrogenation of H2O molecules to generate ·OH, and inhibits the further oxidation of ·OH to generate O2, thereby achieving the efficient degradation of organic wastewater mediated by ·OH.

[0010] The metal ion M is Ni, Cu, or Zn.

[0011] In the above method for treating organic wastewater using electron-rich spinel anodes, preferably, the molar ratio of metal ions M to Co is (0.05-0.2):1.

[0012] In the above method for treating organic wastewater using an electron-rich spinel anode, preferably, the metal ion M is Cu, and the molar ratio of Cu to Co is (0.08-0.1):1. More preferably, the molar ratio of Cu to Co is 0.1:1.

[0013] In this invention, our research indicates that the amount of metal ions M with high electron filling density has a crucial impact on anode performance. Too much or too little M ion will affect its effectiveness and the mechanism of anode operation. Taking copper as an example, insufficient copper content results in weak repulsion between copper and oxygen atoms, which is detrimental to the construction of electron-rich Co. Oh 3+ The center is not conducive to weakening Co. Oh 3+ The binding strength between the site and oxygen-containing substances; *OH is easily peroxidized to produce oxygen. Excessive copper usage will lead to Co... Oh 3+ The presence of too many electrons in the surrounding area weakens Co. Oh 3+The binding energy with H2O inhibits the formation of ·OH. That is, if the amount of metal ion M is too large or too small, it will change the water oxidation pathway, inhibiting the formation of ·OH. This changes the water oxidation pathway from *H2O→*OH→·OH in this invention to *H2O→*OH→*O→O2. After water oxidation generates *OH, desorption cannot occur, and it will be over-oxidized to O2. In this case, the oxygen evolution performance of the material is good. Reasonably controlling the amount of metal ion M is beneficial to the formation of ·OH, and after water oxidation generates *OH, it will quickly desorb into free ·OH and will not continue to oxidize to O2. In this case, the oxygen evolution performance of the material is extremely poor. Therefore, in this invention, it is necessary to precisely control the molar ratio of metal ion M to Co. More preferably, the metal ion M is Cu, and the molar ratio of Cu to Co is (0.08-0.1):1. Even more preferably, the molar ratio of Cu to Co is 0.1:1.

[0014] In the above-mentioned method for treating organic wastewater using electron-rich spinel anodes, preferably, the preparation method of the electron-rich spinel anode includes the following steps: mixing ethylene glycol, copper source, cobalt source and deionized water evenly, then adding urea, hexadecyltrimethylammonium bromide and ammonium fluoride, and continuing to stir evenly until a transparent solution is obtained; immersing an FTO substrate in the above transparent solution, then placing it in a reaction vessel with the conductive surface facing upwards, and carrying out a hydrothermal reaction; after the reaction is completed, naturally cooling, washing with water, drying, and calcining to obtain the electron-rich spinel anode.

[0015] The preparation method of the present invention is advantageous for preparing electron-rich Co. Oh 3+ The electron-rich spinel anode at the center, the above process route and raw material types are conducive to the preparation of the specific electron-rich spinel anode of the present invention.

[0016] In the above-mentioned method for treating organic wastewater using electron-rich spinel anodes, preferably, the FTO substrate is first ultrasonically cleaned in acetone and ethanol solutions, then ultrasonically cleaned with deionized water, and then dried.

[0017] In the above-described method for treating organic wastewater using electron-rich spinel anodes, preferably, the volume ratio of ethylene glycol, copper source, cobalt source, and deionized water is 8-10:2:5:30, wherein the molar concentration ratio of copper source to cobalt source is (0.5-2):4, the mass ratio of urea, hexadecyltrimethylammonium bromide, and ammonium fluoride is 0.5:0.5:(1.4-1.5), and the ratio of urea to ethylene glycol is 8-10 mL:0.5 g. More preferably, the volume ratio of ethylene glycol, copper source, cobalt source, and deionized water is 10:2:5:30, wherein the molar concentration ratio of copper source to cobalt source is (0.5-2):4, the mass ratio of urea, hexadecyltrimethylammonium bromide, and ammonium fluoride is 0.5:0.5:1.455, and the ratio of urea to ethylene glycol is 10 mL:0.5 g.

[0018] In the above-described method for treating organic wastewater using electron-rich spinel anodes, preferably, the hydrothermal reaction temperature is controlled at 110-130℃ and the reaction time is 10-14 hours. More preferably, the hydrothermal reaction temperature is controlled at 120℃ and the reaction time is 12 hours.

[0019] In the above-mentioned method for treating organic wastewater using electron-rich spinel anodes, preferably, the calcination is performed in two stages: first, calcination at 340-360℃ for 1.5-2.5 hours, and then calcination at 540-560℃ for 1.5-2.5 hours. More preferably, calcination is first performed at 350℃ for 2 hours, and then calcination is performed at 550℃ for 2 hours.

[0020] In this invention, the aforementioned process parameters, including the types and proportions of raw materials, as well as the control of hydrothermal reaction parameters and calcination conditions, are beneficial for constructing electron-rich Co in electron-rich spinel anodes. Oh 3+ The center is conducive to preparing the electron-rich spinel anode required by this invention.

[0021] In the above-mentioned method for treating organic wastewater using electron-rich spinel anodes, preferably, when using electron-rich spinel anodes to electrolyze organic wastewater, the electron-rich spinel anode is used as the working electrode, the counter electrode is a Pt sheet, the reference electrode is Ag / AgCl, and the electrolysis voltage is 1.5-2.5V vsAg / AgCl. A constant voltage is provided by an electrochemical workstation (CHI 760E, Shanghai Chenhua, China). Before the reaction begins, both electrodes are inserted into the solution, and the immersion area of ​​the working electrode is 3.75-4.25 cm². 2 The reaction time is 2-2.5 hours. Stirring is maintained throughout the reaction. The solution is drawn up with a syringe, filtered through a 0.45 μm polytetrafluoroethylene (PTFE) membrane, and the reaction solution is collected.

[0022] In the above-mentioned method for treating organic wastewater using electron-rich spinel anodes, preferably, the electrolysis reactor is a 100-150 mL single-chamber electroreactor, and the concentration of pollutants in the organic wastewater is 10-20 mg / L. -1 .

[0023] This invention modifies traditional spinel oxides by modifying Cu... 2+ Introducing metals into tetrahedral sites in Co3O4 to construct electron-rich Co Oh 3+ The center improved B Oh 3+ Electron orbital occupancy at position Cu. 2+ For example, specifically, due to Cu 2+ The electron orbit is 3d 9 (e 4 t2 5 Therefore, in spinel oxides, Cu 2+ The interaction between Co and O atoms involves electron repulsion, while Co... 3+ There is a π contribution between Cu and O atoms. Cu is introduced into Co3O4. 2+ Cu can effectively couple electron repulsion and π contribution. 2+ Electrons are more inclined to octahedral Co 3+ It is conducive to the formation of Co Oh 3+ Rich in electron centers, thus improving B Oh 3+ Electron orbital occupancy at position Co 3+ The binding energy with oxygen-containing substances is reduced, which promotes the rapid desorption of adsorbed *OH into free ·OH, resulting in efficient oxidation of pollutants and high utilization rate of ·OH.

[0024] In this invention, Ni 2+ / Cu 2+ / Zn 2+ By introducing tetrahedral sites from Co3O4, electron-rich Co can be constructed. Oh 3+ Center, weaken Co Oh 3+ The binding strength between the site and oxygen-containing substances releases ·OH for pollutant oxidation. Due to Ni 2+ / Cu 2+ / Zn 2+ The electron orbitals are 3d 8 (e 4 t2 3 ), 3d 9 (e 4 t2 5 ), 3d 10 (e 4t2 5 Therefore, M in spinel oxide 2+ The interaction between Co and O atoms is an electron repulsion, while Co... 3+ There is a π-contribution effect between Cu and O atoms. Introducing Cu into Co3O4 2+ It can effectively couple electron repulsion and π-donation effects, which is beneficial for the formation of Co. Oh 3+ Electron-rich center. Through systematic experiments and electrochemical characterization, the generation efficiency of ·OH and pollutant removal performance in the electrochemical oxidation system were investigated. The results show that the electron-rich spinel anode of this invention has excellent performance. This invention provides a theoretical basis for a deeper understanding of the formation of active substances in electrochemical oxidation systems and provides guidance for the design and synthesis of high-performance and stable wastewater purification electrodes.

[0025] The spinel oxide anode synthesized in this invention can efficiently remove a variety of organic pollutants, with a lower barrier to the generation of ·OH. The electron-rich spinel anode system constructed in this invention achieves efficient ·OH generation while inhibiting its peroxidation to O2, providing a theoretical and technical basis for the treatment of organic wastewater.

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] In the method for treating organic wastewater using an electron-rich spinel anode of this invention, a specific electron-rich spinel anode can effectively promote the rate-limiting step of H2O oxidation to ·OH, thus achieving efficient treatment of organic wastewater. Furthermore, the rational selection of reaction conditions in this system can effectively achieve efficient degradation of pollutants in organic wastewater while strictly inhibiting the further oxidation of ·OH to O2, thereby preventing the loss of its oxidizing capacity. This effectively solves the problem of slow kinetics in the oxidation of H2O to ·OH in traditional electro-oxidation systems, opening up a stable and efficient new method for wastewater treatment. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 For different Cu 2+ Cu doping concentration x Co 3-x Performance diagram of Rhodamine B degradation by O4 anodic anode.

[0030] Figure 2 Cu under different applied constant voltagesx Co 3-x Performance diagram of Rhodamine B degradation by O4 anodic anode.

[0031] Figure 3 The transition metal concentration is 0.1 mol L. -1 The degradation performance of Rhodamine B by Co3O4 with different transition metal doping is shown in the figure.

[0032] Figure 4 For different Cu 2+ Cu doping concentration x Co 3-x Schematic diagram of the electrochemically active surface area of ​​the O4 anode.

[0033] Figure 5 For different Cu 2+ Cu doping concentration x Co 3-x Schematic diagram of the cumulative concentration of ·OH in the O4 anode system.

[0034] Figure 6 Cu x Co 3-x Circulation experiment diagram of Rhodamine B degradation in O4 anode system.

[0035] Figure 7 Cu x Co 3-x Experimental diagram of active species quenching during the removal of Rhodamine B in the O4 anode system.

[0036] Figure 8 For different Cu 2+ Cu doping concentration x Co 3-x EPR spectrum of the O4 anode system.

[0037] Figure 9 Cu x Co 3-x Degradation performance of different pollutants in the O4 anode system. Detailed Implementation

[0038] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0039] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0040] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0041] The specific methods for determining the content of each product in this invention are as follows:

[0042] The concentration change of Rhodamine B was determined at a wavelength of 554 nm using a UV-Vis spectrophotometer. The UV-Vis spectrophotometer used was a U-3900, Hitachi Ltd., Japan.

[0043] The concentration of hydroxylated products and the cumulative concentration of ·OH were determined by high-performance liquid chromatography (HPLC). The HPLC model used was HPLC-LC-20A, Shimadzu, Japan.

[0044] Example 1:

[0045] With Cu x Co 3-x Taking O4 as an example, Rhodamine B was selected as the treatment target, which is a typical pollutant in dyeing and printing wastewater.

[0046] In this embodiment, Rhodamine B, commonly found in typical dyeing and printing wastewater, is used as the treatment target. First, 10-20 mg / L of [amount of solution is missing] is prepared. -1 Rhodamine B, 50 mL, was measured into a beaker. 50 mM sodium sulfate was added to the beaker. After stirring to dissolve, the solution was poured into a 100-150 mL reactor. Subsequently, Cu... x Co 3-x O4 was used as the working electrode, Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode. A constant voltage was applied and the mixture was stirred to initiate the reaction. During the reaction, samples were taken with a syringe at specified time intervals and immediately filtered through a 0.45μm polytetrafluoroethylene (PTFE) membrane.

[0047] The specific preparation method of the anode material in this embodiment is as follows:

[0048] First, take a piece of FTO (1.5cm × 4cm) and sonicate it in acetone and ethanol solutions for 15 minutes each, then sonicate it twice with deionized water and dry it at 60℃. Add 10mL of ethylene glycol and 2mL of 0.1mol / L... -1 Copper nitrate solution, 5 mL 0.4 mol / L -1Cobalt nitrate solution and 30 mL of deionized water were mixed to form a homogeneous solution. Then, 0.500 g of urea, 0.050 g of hexadecyltrimethylammonium bromide, and 1.455 g of ammonium fluoride were added, and stirring continued until a homogeneous and transparent solution was obtained. The pretreated FTO was then immersed in the lining of a 100 mL reactor containing the above solution, with the conductive side facing upwards, and stored at 120 °C for 12 h. After natural cooling, the electrode was removed and washed with deionized water. After drying, the electrode was placed in a muffle furnace and calcined at 350 °C and 550 °C for 2 h each, and then cooled to room temperature to finally obtain Cu. x Co 3-x O4 electrode material (where the molar ratio of copper to cobalt is 0.1:1).

[0049] Change the volume of copper nitrate solution to 0.05 mol / L. -1 and 0.15 mol L -1 Cu were prepared separately. x Co 3-x O4-1 (copper to cobalt molar ratio of 0.05:1) and Cu x Co 3-x O4-3 (molar ratio of copper to cobalt is 0.15:1).

[0050] Example 2:

[0051] With Zn x Co 3-x Taking O4 as an example, Rhodamine B was selected as the treatment target, which is a typical pollutant in dyeing and printing wastewater.

[0052] In this embodiment, Rhodamine B, commonly found in typical alkaline dyeing and printing wastewater, is used as the treatment target. First, 10-20 mg / L of [amount missing] is prepared... -1 Rhodamine B, 50 mL, was measured into a beaker. 50 mM sodium sulfate was added to the beaker. After stirring to dissolve, the solution was poured into a 100-150 mL reactor. Subsequently, Zn... x Co 3-x O4 was used as the working electrode, Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode. A constant voltage was applied while stirring to initiate the reaction. During the reaction, samples were taken with a syringe at specified time intervals and immediately filtered through a 0.45μm polytetrafluoroethylene (PTFE) membrane.

[0053] The specific preparation method of the anode material in this embodiment is as follows:

[0054] First, take a piece of FTO (1.5cm × 4cm) and sonicate it in acetone and ethanol solutions for 15 minutes each, then sonicate it twice with deionized water and dry it at 60℃. Add 10mL of ethylene glycol and 2mL of 0.1mol / L... -15 mL of zinc nitrate solution (0.4 mol / L) -1 Cobalt nitrate solution and 30 mL of deionized water were mixed to form a homogeneous solution. Then, 0.500 g of urea, 0.050 g of hexadecyltrimethylammonium bromide, and 1.455 g of ammonium fluoride were added, and stirring continued until a homogeneous and transparent solution was obtained. Clean FTO was then immersed in a 100 mL reactor liner containing the above solution, with the conductive side facing upwards. After sealing, the electrode was transferred to a drying oven and stored at 120 °C for 12 h. After natural cooling, the electrode was removed and washed with deionized water. After drying, the electrode was placed in a muffle furnace and calcined at 350 °C and 550 °C for 2 h each, and then cooled to room temperature to finally obtain Zn. x Co 3-x O4 electrode material (in which the molar ratio of zinc to cobalt is 0.1:1).

[0055] Example 3:

[0056] Take Ni x Co 3-x Taking O4 as an example, Rhodamine B was selected as the treatment target, which is a typical pollutant in dyeing and printing wastewater.

[0057] In this embodiment, Rhodamine B, commonly found in typical alkaline dyeing and printing wastewater, is used as the treatment target. First, 10-20 mg / L of [amount missing] is prepared... -1 Rhodamine B, 50 mL, was measured into a beaker. 50 mM sodium sulfate was added to the beaker. After stirring to dissolve, the solution was poured into a 100-150 mL reactor. Subsequently, Ni... x Co 3-x O4 was used as the working electrode, Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode. A constant voltage was applied while stirring to initiate the reaction. During the reaction, samples were taken with a syringe at specified time intervals and immediately filtered through a 0.45μm polytetrafluoroethylene (PTFE) membrane.

[0058] The specific preparation method of the anode material in this embodiment is as follows:

[0059] First, take a piece of FTO (1.5cm × 4cm) and sonicate it in acetone and ethanol solutions for 15 minutes each, then sonicate it twice with deionized water and dry it at 60℃. Add 10mL of ethylene glycol and 2mL of 0.1mol / L... -1 Nickel nitrate solution, 5 mL 0.4 mol / L -1Cobalt nitrate solution and 30 mL of deionized water were mixed to form a homogeneous solution. Then, 0.500 g of urea, 0.050 g of hexadecyltrimethylammonium bromide, and 1.455 g of ammonium fluoride were added, and stirring continued until a homogeneous and transparent solution was obtained. Clean FTO was then immersed in a 100 mL reactor liner containing the above solution, with the conductive side facing upwards. After sealing, the electrode was transferred to a drying oven and stored at 120 °C for 12 h. After natural cooling, the electrode was removed and washed with deionized water. After drying, the electrode was placed in a muffle furnace and calcined at 350 °C and 550 °C for 2 h each, and then cooled to room temperature to finally obtain Ni. x Co 3-x O4 electrode material (where the molar ratio of nickel to cobalt is 0.1:1).

[0060] The degradation effect of the present invention on Rhodamine B and its mechanism of action are discussed in detail below through the specific experimental results of Examples 1-3.

[0061] like Figure 1 As shown, the degradation performance of Rhodamine B in different catalytic systems was compared. Under constant voltage conditions, Cu x Co 3-x The O4 system can remove almost 100% of Rhodamine B within 2 hours, which is far superior to Co3O4 and CuCo2O4 (reaction conditions: initial voltage 2V, sodium sulfate concentration 50mM, Rhodamine B concentration 10mg / L). -1 The preparation process of CuCo2O4 is the same as in Example 1, except that the amount of copper source is increased. Meanwhile, by adjusting the amount of different copper sources (where Cu... x Co 3-x The amount of copper source used in O4-1 is 0.05 mol L. -1 Cu x Co 3-x The amount of copper source used in O4-3 was 0.15 mol L. -1 The results showed that different amounts of copper source had a significant impact on the degradation performance of Rhodamine B. When the amount of copper source was 0.1 mol / L... -1 At that time, the degradation performance is optimal.

[0062] like Figure 2 As shown, by setting different voltage conditions, it was found that when the applied voltage is 2V, Cu x Co 3-x The O4 system exhibits the best performance in degrading Rhodamine B. For example... Figures 3-5 As shown, with an applied voltage of 2V and an introduced transition metal concentration of 0.1 mol / L... -1 At that time, only Cu x Co 3-x The O4 system can remove almost 100% of Rhodamine B within 2 hours, indicating that Cu 2+The introduction of [something] is more conducive to the construction of electron-rich Co. Oh 3+ The Co3O4 site. Combining the electrochemically active surface area and the cumulative concentration of ·OH, it can be concluded that Cu... x Co 3-x The electrochemically active surface area of ​​O4 can reach 11.56 mF cm⁻¹. -2 And the cumulative concentration of ·OH is the highest, because Cu 2+ The electron orbit is 3d 9 (e 4 t2 5 Therefore, in Co3O4, Cu 2+ The interaction between Co and O atoms involves electron repulsion, while Co... 3+ There is a π contribution between Cu and O atoms. Cu is introduced into Co3O4. 2+ It can effectively couple electron repulsion and π contribution, which is beneficial for the formation of Co. Oh 3+ Rich electron centers weaken Co Oh 3+ The binding strength between the site and oxygen-containing substances is determined, releasing ·OH. Furthermore, the Cu content was measured. x Co 3-x Cyclic experiments on the degradation of Rhodamine B in the O4 system, such as Figure 6 As shown, the average removal rate after 7 cycles was about 94%, indicating that the system has high electrochemical stability.

[0063] Figure 7 and Figure 8 Cu was shown x Co 3-x Active species in the O4 system. Quenching experiments of active species were conducted using tert-butanol (TBA) as a hydroxyl radical quencher and methanol (MeOH) as a hydroxyl radical and sulfate radical quencher, respectively. In Cu... x Co 3-x The O4 system was tested with the addition of a quencher, and preliminary results indicated that ·OH is the main active species in the degradation process of organic pollutants. Figure 8 In the EPR test, a small amount of liquid was removed during the reaction, and 5,5-dimethyl-1-pyrrolino-N-oxide (DMPO) scavenging agent was added. The signal peak of DMPO-·OH was then tested. The results showed that a strong DMPO-·OH signal existed during the reaction, further indicating that ·OH is the main active species in the degradation process of organic pollutants. The strong oxidizing ability of this active species can rapidly attack organic pollutants and degrade them in a short time.

[0064] like Figure 9 As shown, Cu was tested. x Co 3-xThe degradation performance of the O4 system for different pollutants was investigated. Results showed that the system exhibited excellent degradation performance for both electron-withdrawing pollutants (NB: nitrobenzene), and electron-donating pollutants (PE: phenol, CBZ: carbamazepine, TC: tetracycline, SMX: sulfamethoxazole, 4-CP: p-chlorophenol). (Reaction conditions: initial voltage 2V, sodium sulfate concentration 50mM, pollutant concentration 10mg / L) -1 This demonstrates that the system has broad application potential in actual water pollution treatment.

[0065] As can be seen from the above embodiments, the present invention constructs an electron-rich B... Oh 3+ An electrochemical oxidation system using spinel to oxidize H₂O has achieved rapid degradation of organic pollutants in wastewater. In this system, due to the excellent electrochemical activity and tunable electronic structure of spinel oxide, A… Td 2+ and B Oh 3+ Strong electron delocalization between sites can effectively induce H2O in B Oh 3+ Oxidation to ·OH at the site. Furthermore, Cu 2+ Electron repulsion between Co and O atoms and Co 3+ The π-donating effect between the O atom and the Co atom, and the effective coupling between the two promotes the formation of Co. Oh 3+ Rich electron centers weaken Co Oh 3+ The binding strength between the site and oxygen-containing substances, and the released ·OH, make Cu x Co 3-x O4 has excellent electrochemical oxidation performance and has great application prospects in the field of practical organic wastewater treatment.

Claims

1. A method for treating organic wastewater using an electron-rich spinel anode, characterized in that, Includes the following steps: Electrolysis of organic wastewater is performed using an electron-rich spinel anode. The electron-rich spinel anode involves introducing metal ions M with high electron filling density into the tetrahedral sites of Co3O4, enabling effective coupling of M... Td 2+ Electron repulsion between O atoms and Co Oh 3+ The π contribution between the O atom and the electron-rich Co atoms constructs an electron-rich Co. Oh 3+ Center, weaken Co Oh 3+ The binding strength between the site and oxygen-containing substances induces the oxidation and dehydrogenation of H2O molecules to generate •OH, and inhibits the further oxidation of •OH to generate O2, thereby achieving the efficient degradation of organic wastewater mediated by •OH. The metal ion M is Ni, Cu, or Zn; The molar ratio of the metal ion M to Co is (0.05-0.2):

1.

2. The method for treating organic wastewater using an electron-rich spinel anode according to claim 1, characterized in that, The metal ion M is Cu, and the molar ratio of Cu to Co is (0.08-0.1):

1.

3. The method for treating organic wastewater using an electron-rich spinel anode according to claim 1 or 2, characterized in that, The preparation method of the electron-rich spinel anode includes the following steps: ethylene glycol, copper source, cobalt source and deionized water are mixed evenly, then urea, hexadecyltrimethylammonium bromide and ammonium fluoride are added, and the mixture is stirred evenly until a transparent solution is obtained; the FTO substrate is immersed in the above transparent solution, and then placed in a reaction vessel with the conductive surface facing upward, and a hydrothermal reaction is carried out; after the reaction is completed, the substrate is naturally cooled, washed with water, dried and then calcined to obtain the electron-rich spinel anode.

4. The method for treating organic wastewater using an electron-rich spinel anode according to claim 3, characterized in that, The FTO substrate is first ultrasonically cleaned in acetone and ethanol solutions, then ultrasonically cleaned with deionized water, and finally dried.

5. The method for treating organic wastewater using an electron-rich spinel anode according to claim 4, characterized in that, The volume ratio of ethylene glycol, copper source, cobalt source, and deionized water is 8-10:2:5:30, wherein, The molar concentration ratio of copper source to cobalt source is (0.5-2):4, the mass ratio of urea, hexadecyltrimethylammonium bromide and ammonium fluoride is 0.5:0.05:(1.4-1.5), and the ratio of ethylene glycol to urea is 8-10 mL:0.5 g.

6. The method for treating organic wastewater using an electron-rich spinel anode according to claim 4, characterized in that, During the hydrothermal reaction, the reaction temperature is controlled at 110-130℃ and the reaction time is 10-14h.

7. The method for treating organic wastewater using an electron-rich spinel anode according to claim 4, characterized in that, The calcination process involves two stages: first, calcination at 340-360℃ for 1.5-2.5 hours, and then calcination at 540-560℃ for 1.5-2.5 hours.

8. The method for treating organic wastewater using an electron-rich spinel anode according to claim 1 or 2, characterized in that, When using an electron-rich spinel anode to electrolyze organic wastewater, the electron-rich spinel anode is used as the working electrode, the counter electrode is a Pt sheet, the reference electrode is Ag / AgCl, and the electrolysis voltage is 1.5-2.5V vs Ag / AgCl.

9. The method for treating organic wastewater using an electron-rich spinel anode according to claim 1 or 2, characterized in that, The electrolysis reactor is a single-chamber electroreactor with a capacity of 100-150 mL, and the concentration of pollutants in the organic wastewater is 10-20 mg / L. -1 .

Images