A system for efficient pollutant degradation by electrocatalytic ozone oxidation using foamed copper-based copper oxide nanowires as cathode

Abstract

The present invention belongs to the field of sewage treatment and relates to a system for efficient pollutant degradation through electrocatalytic ozone oxidation using foamed copper-based copper oxide nanowires as cathodes. This invention is the first to use foamed copper-based copper oxide nanowires as cathodes in an electrocatalytic ozone oxidation system. The foamed copper-based copper oxide nanowires as cathodes can catalyze ozone to produce a large number of hydroxyl radicals, superoxide radicals, and other oxidants, thereby significantly improving the pollutant removal and mineralization effects of the electrocatalytic ozone oxidation system, especially the efficient removal of TOC. The electrocatalytic ozone system using foamed copper-based copper oxide nanowires as cathodes couples electrocatalytic oxidation technology with ozone oxidation technology, transforming a single chemical oxidation process in the water treatment process into multiple chemical oxidation processes and multiple advanced oxidation processes that may produce hydroxyl radicals. This system is used for the advanced treatment of industrial wastewater and has the advantages of fast reaction rate, strong oxidation capacity, and stable treatment effects, and has good application prospects.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment and relates to a system for efficiently degrading pollutants by electrocatalytic ozone oxidation using foamed copper-based copper oxide nanowires as cathodes. Background Art

[0002] Ozone is a strong oxidant. Ozone oxidation and advanced oxidation technologies are commonly used for the advanced treatment of industrial wastewater. Ozone oxidation primarily operates through direct oxidation, a highly selective process that is particularly effective against unsaturated aliphatic and aromatic hydrocarbons, effectively breaking, ring-opening, and decomposing organic pollutants. However, ozone's complete mineralization of organic pollutants is not evident.

[0003] In the electro-ozonation system, the traditional electro-ozonation system uses stainless steel or titanium as the cathode to generate O3 through the electro-reduction of ozone. - , O3 - It reacts with water to generate hydroxyl radicals. This process can enhance the oxidizing ability of ozone and further degrade organic pollutants. However, the ability of the electro-ozone oxidation system with stainless steel or titanium as the cathode to completely mineralize pollutants is extremely limited. The flat cathode electrode (stainless steel or titanium) has problems such as limited specific surface area and low catalytic activity, and is not an ideal cathode electrocatalytic material. In the electrocatalytic ozone coupled oxidation system, the cathode is the one that produces O3 - The core of the electrocatalytic ozone-coupled oxidation system lies in the presence of oxidants such as hydroxyl radicals and oxidants such as chlorinated ... Summary of the Invention

[0004] The present invention provides a system and method for electrocatalytic ozone treatment of high-efficiency organic pollutants using a copper foam-based copper oxide nanowire cathode (CuO NWs / CF). The cathode is a copper foam-based copper oxide nanowire cathode, and the anode is a ruthenium-iridium-titanium electrode or a platinum electrode. The copper foam-based copper oxide nanowire cathode catalyzes ozone to produce large amounts of hydroxyl radicals, superoxide radicals, and other oxidants, significantly improving the pollutant degradation performance of the electrocatalytic ozone oxidation system.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] The present invention provides an application of copper oxide nanowires in an electrocatalytic ozone oxidation system. The application is that, in the electrocatalytic ozone oxidation system, foamed copper-based copper oxide nanowires are used as cathodes, and the foamed copper-based copper oxide nanowires are in-situ generated copper oxide nanowires by a thermal oxidation method.

[0007] In the above technical solution, further, the anode of the electrocatalytic ozone oxidation system is a ruthenium-iridium-titanium electrode or a platinum electrode.

[0008] In the above technical solution, further, the cathode and anode of the electrocatalytic ozone oxidation system are flat plates placed opposite to each other, and the distance between the electrodes is 2-3 cm.

[0009] In the above technical solution, further, the method for preparing the copper oxide nanowires includes: calcining the foam copper substrate at a calcination temperature of 400-500°C.

[0010] In the above technical solution, further, in the electrocatalytic ozone oxidation system, the ozone concentration is 20-80 mg / L; the DC current density is 5-20 mA / cm 2 .

[0011] The present invention also provides an electrocatalytic ozone oxidation system, comprising a cathode, an anode, and an aeration device. The cathode is a foam copper-based copper oxide nanowire cathode, and the foam copper-based copper oxide nanowire is a foam copper-based copper oxide nanowire generated in situ by a thermal oxidation method.

[0012] In the above technical solution, further, the method for preparing copper oxide nanowires includes: calcining a foam copper substrate at a calcination temperature of 400-500°C, forming a layer of copper oxide on the outer surface of the foam copper after treatment, and the oxide morphology is nanowires,

[0013] In the above technical solution, further, the anode is a platinum electrode or a ruthenium-iridium-titanium electrode.

[0014] In the above technical solution, further, the cathode and the anode are flat plates placed opposite each other, and the distance between the electrodes is 2-3 cm; and the aeration device is located between the cathode and the anode.

[0015] In the above technical solution, further, the method for degrading organic pollutants by the electrocatalytic ozone oxidation system is as follows: 20-80 mg / L ozone is introduced into the aeration device, and a direct current is introduced with a current density of 5-20 mA / cm 2 .

[0016] Compared with the prior art, the present invention has the following beneficial effects: the present invention is the first to use foamed copper-based copper oxide nanowires as cathodes for electrocatalytic ozone oxidation systems, giving the cathodes of the electrocatalytic ozone oxidation systems the ability to heterogeneously catalyze ozone, and being able to catalyze ozone to produce a large number of hydroxyl radicals, superoxide radicals and other oxidants, thereby significantly improving the pollutant removal and mineralization of the electrocatalytic ozone oxidation system, especially the efficient removal of TOC; and the foamed copper-based copper oxide nanowire cathode, as a three-dimensional mesh pore structure material, has a large surface area and permeability, and the outer oxide morphology is nanowires, and it also has good electrical conductivity and ozone catalytic performance.

[0017] The electrocatalytic ozone system of the present invention uses foamed copper-based copper oxide nanowires as the cathode, couples electrocatalytic oxidation technology with ozone oxidation technology, and converts a single chemical oxidation process in the water treatment process into multiple chemical oxidation processes and multiple advanced oxidation processes that may produce hydroxyl free radicals. It is used for the deep treatment of industrial wastewater, has the advantages of fast reaction rate, strong oxidation ability, and stable treatment effect, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 SEM images of foamed copper-based copper oxide nanowires (CuO NWs / CF) produced at different calcination temperatures in the examples;

[0019] Figure 2 XRD patterns of foamed copper-based copper oxide nanowires (CuO NWs / CF) generated at different calcination temperatures in the examples;

[0020] Figure 3 XPS graphs of foamed copper-based copper oxide nanowires (CuO NWs / CF) generated at different calcination temperatures in the examples;

[0021] Figure 4 The TOC removal performance of the electrocatalytic ozone system using different cathodes (CuO NWs / CF) in the embodiment is shown;

[0022] Figure 5 The removal performance of phenol in the electrocatalytic ozone system using different cathodes (CuO NWs / CF) in the examples is shown;

[0023] Figure 6 The TOC removal efficiency of the CuO NWs / CF cathode electrocatalytic ozone oxidation system after 10 cycles;

[0024] Figure 7 The COD removal efficiency of the electrocatalytic ozone system using a copper foam-based copper oxide nanowire cathode (CuO NWs / CF) in treating industrial wastewater in the embodiment;

[0025] Figure 8is the metal dissolution amount of the CuO NWs / CF cathode electrocatalytic ozone oxidation system after 10 cycles;

[0026] Figure 9 Mechanism diagram of the electrocatalytic ozone oxidation system. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to specific examples, but the present invention is not limited thereto in any way.

[0028] Example 1

[0029] Preparation of foam copper-based copper oxide nanowires, the specific preparation method is as follows:

[0030] The foam copper (3×3×0.15cm 3 , pore size 0.1 mm) were immersed in hydrochloric acid solution (1 mol·L -1 ), acetone solution, anhydrous ethanol, and ultrapure water, and ultrasonically cleaned for 10 minutes. Most of the water was blown off with nitrogen, and the remaining water was removed in a freeze-drying oven for 1 hour. The pretreated copper foam was placed in a muffle furnace and heated at 10°C / min to 200°C, 300°C, and 400°C for 30 minutes to prepare a copper foam cathode.

[0031] like Figure 1 The copper oxide nanowire cathodes prepared by the above method were characterized by scanning electron microscopy. It can be seen that cuprous oxide microcrystals are generated on the surface of the foam copper at a calcination temperature of 200°C. At a calcination temperature of 300°C, the surface of the foam copper is covered with small round copper oxide crystal particles. When the calcination temperature is 400°C, the surface of the foam copper is covered with a "fluffy" nanowire array, and the diameter of the nanowire gradually decreases from the root to the tip, obtaining foam copper-based copper oxide nanowires CuO NWs / CF.

[0032] Figure 2 and Figure 3 These are the XRD patterns and XPS patterns of the in-situ grown copper oxide nanowire cathode at different calcination temperatures, showing that the oxidation degree of the foam copper gradually increases with the increase of calcination temperature.

[0033] Example 2

[0034] The copper-based copper oxide nanowire foam prepared in Example 1 at a calcination temperature of 400°C was used as the cathode, and the anode was a ruthenium-iridium-titanium anode (3×3×0.15 cm 3), the cathode and anode have long handles above the water surface to prevent the electrode clamps from getting wet and causing side reactions. The cathode and anode are flat plates placed opposite each other, with a 2.7 cm distance between the electrodes. The electrolyte in the reaction tank is 0.05M Na2SO4. The aeration head used in this example is made of cylindrical glass with an anti-backflow device in the upper middle portion and a frosted glass aeration surface with a diameter of 1 cm. The above-mentioned electrocatalytic ozone oxidation system is used to treat organic matter.

[0035] The pollutant used was a 50 mg / L phenol solution, and the current density applied to the system was 10 mA / cm 2 The system was operated at a constant current of 1000 nm and simultaneously introduced 40 mg / L ozone gas at a flow rate of 0.1 L / min. The reaction was continued for 0.5 h, and the TOC removal rate was measured. Under these conditions, the TOC removal rate of the system was 99.31%.

[0036] Example 3

[0037] The system of Example 2 was used to compare the effects of ozone (O3) alone, the electro-ozone oxidation (EO) system with stainless steel as the cathode, the electro-catalytic ozone oxidation system with copper foam (CF) as the cathode, and the electro-catalytic ozone oxidation system (ECO) with copper foam calcined at different temperatures (CuO 200℃ / CF, CuO 300℃ / CF, CuO 400℃ / CF) as the cathode in removing the pollutant phenol. The initial concentration of phenol was 50 mg / L. The six groups of experiments were conducted at pH 6 and a current density of 10 mA / cm 2 , after treatment for 0.5h under the conditions of ozone concentration of 40mg / L and ozone flow rate of 0.1L / min, the experimental results are as follows:

[0038]

[0039] Figure 4 and Figure 5 The total organic carbon removal efficiency and phenol concentration reduction effect of phenol under different oxidation systems are shown respectively. From the test results, it can be seen that the electrocatalytic ozone oxidation system with copper foam-based copper oxide nanowires calcined at 400°C as the cathode (CuONWs / CF) in this embodiment has the highest efficiency.

[0040] Example 4

[0041] The following experiments were conducted using the foamed copper-based copper oxide nanowires (CuO NWs / CF) prepared in Example 1 and calcined at 400° C. as a cathode.

[0042] Cyclic experiment: The electrocatalytic ozone oxidation system of copper foam-based copper oxide nanowires as cathode (CuO NWs / CF) was operated at pH 6, 0.05 M Na2SO4 electrolyte, 40 mg / L ozone concentration, 0.1 L / min ozone flow rate, and 10 mA / cm2 current density.2 Run 10 cycles under the same conditions. Figure 6 The TOC removal rate of the system after 10 cycles was shown. The initial phenol concentration was 50 mg / L. In the 10th cycle, the TOC removal rate of phenol decreased by 8.1%, indicating that the system has good stability.

[0043] Actual wastewater treatment effect: Pharmaceutical wastewater with a pH of 9.3, a salt content of 850 mg / L, and a COD value of 150 mg / L was selected as the treated wastewater. 0.05 M Na2SO4 electrolyte was added, and an electrocatalytic ozone oxidation system with foamed copper-based copper oxide nanowires (CuO NWs / CF) as the cathode was used. At an ozone concentration of 40 mg / L and a current density of 10 mA / cm 2 The treatment effect under the conditions Figure 7 This is the actual wastewater treatment effect diagram of the system. At 60 minutes, the COD removal rate is 77.1%.

[0044] Metal ion precipitation: The electrocatalytic ozone oxidation system with copper oxide foam nanowires as cathode (CuO NWs / CF) was measured by inductively coupled plasma optical emission spectrometry (ICP-OES) at pH 6, 0.05 M Na2SO4 electrolyte, 40 mg / L ozone concentration, 0.1 L / min ozone flow rate, and 10 mA / cm2 current density. 2 The degree of copper ion precipitation after treating 50 mg / L phenol solution under the same conditions for half an hour was tested for 10 cycles. Figure 8 The metal dissolution of the CuO NWs / CF cathode electrocatalytic ozone oxidation system during 10 cycles was shown. The concentration of copper ions precipitated was generally between 0.2 and 0.6 mg / L, and occasionally exceeded 1 mg / L.

[0045] The above embodiments are only preferred experimental methods of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. Application of copper oxide nanowires in an electrocatalytic ozone oxidation system, wherein the application is to use foamed copper-based copper oxide nanowires as cathodes in the electrocatalytic ozone oxidation system, wherein the foamed copper-based copper oxide nanowires are in-situ generated copper oxide nanowires by thermal oxidation of the foamed copper-based copper.

2. The use according to claim 1, characterized in that The anode of the electrocatalytic ozone oxidation system is a ruthenium-iridium-titanium electrode or a platinum electrode.

3. The use according to claim 1, characterized in that The cathode and anode of the electrocatalytic ozone oxidation system are flat plates placed opposite to each other, with a distance between the electrodes of 2-3 cm.

4. The use according to claim 1, characterized in that The preparation method of the copper oxide nanowires comprises: calcining a foam copper substrate at a calcination temperature of 400-500°C.

5. The use according to claim 1, characterized in that In the electrocatalytic ozone oxidation system, the ozone concentration is 20-80 mg / L; the DC current density is 5-20 mA / cm 2 .

6. An electrocatalytic ozone oxidation system comprising a cathode, an anode, and an aeration device, characterized in that: The cathode is a foam copper-based copper oxide nanowire cathode, and the foam copper-based copper oxide nanowire is a foam copper-based copper oxide nanowire in-situ generated by a thermal oxidation method.

7. The electrocatalytic ozone oxidation system according to claim 6, characterized in that: The preparation method of the copper oxide nanowires comprises: calcining a foam copper substrate at a calcination temperature of 400-500°C.

8. The electrocatalytic ozone oxidation system according to claim 6, characterized in that: The anode is a platinum electrode or a ruthenium-iridium-titanium electrode.

9. The electrocatalytic ozone oxidation system according to claim 6, characterized in that: The cathode and the anode are flat plates placed opposite to each other, with a distance of 2-3 cm between the electrodes; and the aeration device is located between the cathode and the anode.

10. The method for degrading organic pollutants using an electrocatalytic ozone oxidation system according to claim 6, characterized in that: Introduce 20-80 mg / L ozone into the aeration device and pass direct current with a current density of 5-20 mA / cm 2 .

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