A hydroxyl water treatment system based on electrogenerated hydrogen peroxide

Abstract

This invention provides a hydroxyl water treatment system based on electrogenerated hydrogen peroxide, belonging to the field of electrocatalytic green synthesis and water treatment technology. The hydroxyl water treatment system based on electrogenerated hydrogen peroxide of this invention includes: a hydroxyl water treatment module (1), an anolyte storage tank (14), a first circulation pump (15), a treatment liquid storage tank (16), a second circulation pump (17), a distributor (18), a filter device (19), a water softener (20), a sensor (21), a regulated DC power supply (22), and a control system (23). This invention utilizes oxygen reduction technology and photocatalysis technology to effectively solve the storage, transportation, and safety issues related to the addition of hydrogen peroxide in traditional advanced oxidation water treatment systems using hydrogen peroxide as an intermediate. It has advantages such as high efficiency, environmental friendliness, wide applicability, and ease of automation.

Description

Technical Field

[0001] This invention relates to the fields of electrocatalytic green synthesis and water treatment technology, and in particular to a hydroxyl water treatment system based on electrogenerated hydrogen peroxide. Background Technology

[0002] With the rapid development of modern industry, the types and quantities of organic matter in wastewater are increasing dramatically, and this growth trend is evident. Traditional biological, physical, and chemical treatment methods are insufficient to effectively degrade organic matter in wastewater, while advanced oxidation water treatment technologies, which exhibit excellent mineralization effects on organic pollutants, have received considerable research and application. Advanced oxidation technology utilizes the highly oxidizing hydroxyl radicals generated during chemical reactions and a series of chain reactions to rapidly oxidize and decompose pollutants until they are completely removed. The standard redox potential of hydroxyl radicals is as high as 2.87V, second only to fluorine gas (3.06V), exhibiting higher oxidizing power than other common oxidants. It can degrade organic pollutants in water through dehydrogenation, electrophilic addition, and electron transfer. Therefore, advanced oxidation technology, with its advantages of strong oxidizing power, high efficiency and environmental friendliness, wide applicability, and ease of operation, is considered a highly promising technology for controlling recalcitrant organic pollutants in water bodies.

[0003] Hydrogen peroxide, as a green oxidant containing only hydrogen and oxygen, possesses a strong ability to combine with other catalysts or oxidants to induce free radical chain reactions that generate hydroxyl radicals. Therefore, hydrogen peroxide is widely used in advanced oxidation systems employing multiple technologies as a green intermediate for hydroxyl radicals, such as the Fenton reaction, H₂O₂ / O₃, UV / H₂O₂, and UV / H₂O₂ / O₃. However, the hydrogen peroxide required in these reaction systems is mainly added externally. When the concentration of hydrogen peroxide exceeds 8%, it is classified as a hazardous chemical, and accidents such as hydrogen peroxide solution explosions and corrosion are prone to occur during transportation. Furthermore, the external addition of hydrogen peroxide in advanced oxidation systems also poses the problem of hazardous chemical storage. Therefore, developing advanced oxidation technologies for the in-situ synthesis of hydrogen peroxide is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a hydroxyl water treatment system based on electrogenerated hydrogen peroxide, which can efficiently synthesize hydrogen peroxide in situ.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] The present invention provides a hydroxyl water treatment system based on electrogenerated hydrogen peroxide, comprising: a hydroxyl water treatment module 1, an anolyte storage tank 14, a first circulation pump 15, a treatment liquid storage tank 16, a second circulation pump 17, a distributor 18, a filter device 19, a water softener 20, a sensor 21, a regulated DC power supply 22, and a control system 23.

[0007] The hydroxyl water treatment module 1, the anolyte storage tank 14 and the first circulation pump 15 are sequentially connected to form an anolyte circulation electrolysis path;

[0008] The hydroxyl water treatment module 1, the treatment liquid storage tank 16, the second circulation pump 17, the distributor 18, the filter device 19 and the soft water device 20 are connected in sequence to form a cathode circulating electrolysis path and a first circulating oxidation path.

[0009] The hydroxyl water treatment module 1, the treatment liquid storage tank 16, the second circulation pump 17 and the distributor 18 are connected in sequence to form the second circulation oxidation path.

[0010] The sensor 21 is installed inside the treatment liquid storage tank 16; the control system 23 is connected to the sensor 21 and the regulated DC power supply 22; the regulated DC power supply 22 is connected to the hydroxyl water treatment module 1;

[0011] The hydroxyl water treatment module 1 includes: a cathode side plate 121, a gas diffusion cathode 105, a cathode cavity 2, a proton exchange membrane 125, an anode cavity 3, a fiber titanium anode 106, an isolation plate 129, a hydroxyl oxidation cavity 4, a quartz plate 132, a light source fixing plate 134, and a microcavity plasma ultraviolet light source 107. All components of the hydroxyl water treatment module 1 are connected by bolts.

[0012] The gas diffusion cathode 105 includes a gas diffusion layer 1051, a current collector layer 1052, and a heteroatom-doped carbon catalyst layer 1053 stacked sequentially.

[0013] Furthermore, the hydroxyl water treatment module 1 also includes a first washer 122, a second washer 123, a third washer 124, a fourth washer 126, a fifth washer 127, a sixth washer 128, a seventh washer 130, an eighth washer 131, and a ninth washer 133.

[0014] Furthermore, the anolyte storage tank 14 is connected to the outlet 111 of the anolyte chamber 3; the first circulation pump 15 is connected to the inlet 110 of the anolyte chamber 3; the treatment liquid storage tank 16 is connected to the outlet 113 of the hydroxyl oxidation chamber 4; the distributor 18 is connected to the inlet 112 of the hydroxyl oxidation chamber 4; the soft water device 20 is connected to the inlet 108 of the cathode chamber 2; and the outlet 109 of the cathode chamber 2 is connected to the inlet 112 of the hydroxyl oxidation chamber 4.

[0015] Furthermore, the anolyte in the anolyte storage tank 14 contains an inorganic salt supporting electrolyte, which includes H2SO4, K2SO4, Na2SO4, KNO3, or NaNO3.

[0016] Furthermore, the sensor 21 is a TOC sensor, and the control system 23 sets the current intensity of the regulated DC power supply 22 according to Equation 1:

[0017]

[0018] In Equation 1, I represents the current intensity of the hydroxyl water treatment module 1, mA·cm. -2 n represents the number of electrons transferred during the complete mineralization of organic pollutants; F represents the Faraday electrolysis constant, 96486 C·mol⁻¹. -1 V represents the volume of the hydroxyl oxidation chamber 4, in L; C TOC This indicates the TOC concentration of organic pollutants, in mg·L⁻¹. -1 4.32×10 7 The conversion factor represents the unit homogenization factor; m represents the number of carbon atoms in the organic pollutant; t represents the electrolysis time, in hours.

[0019] Furthermore, the gas diffusion cathode 105 includes a gas diffusion layer, a current collector layer, and a heteroatom-doped carbon catalyst layer stacked sequentially; the carbon material in the heteroatom-doped carbon catalyst layer is conductive carbon black, graphite, carbon nanotubes, graphene, acetylene black, or activated carbon fiber, and the heteroatoms include one or more of N, O, and B; the surface contact angle of the heteroatom-doped carbon catalyst layer is 130° to 150°.

[0020] Furthermore, the substrate of the fiber titanium anode 106 is a fiber titanium felt, the thickness of which is 0.1-0.6 mm and the porosity is 50-90%. A noble metal coating is attached to the surface of the fiber titanium felt, and the chemical composition of the noble metal coating is Pt, RuO2, IrO2, IrO2-Ta2O5, RuO2-TiO2, IrO2-TiO2, IrO2-Ta2O5-TiO2 or SnO2-Sb2O5-IrO2.

[0021] Furthermore, the microcavity plasma ultraviolet light source 107 has a square structure and is fixed within the light source fixing plate 134. The ultraviolet light source wavelength of the microcavity plasma ultraviolet light source 107 is 220–280 nm, and the radiation intensity is 5–10 mW / cm². 2 .

[0022] Furthermore, the anolyte in the anolyte storage tank 14 is transported to the inlet of the anode cavity 3 under the action of the first circulation pump 15, and flows out from the outlet of the anode cavity 3 and returns to the anolyte storage tank 14, and is circulated for electrolysis in sequence. The treatment liquid in the treatment liquid storage tank 16 is partially introduced into the inlet of the hydroxyl oxidation cavity 4 through the splitter 18 under the action of the second circulation pump 17, and the remaining part flows through the filter device 19 and the soft water device 20, and then enters the flow channel inside the cathode cavity 2 through the inlet of the cathode cavity 2. After flowing out from the outlet of the cathode cavity 2, it enters the flow channel inside the hydroxyl oxidation cavity 4 through the inlet of the hydroxyl oxidation cavity 4, oxidizes and decomposes the organic pollutants in the treatment liquid, and then flows back from the outlet of the hydroxyl oxidation cavity 4 to the treatment liquid storage tank 16, and is circulated for oxidation treatment in sequence.

[0023] Furthermore, the ratio of the flow of the treatment liquid in the treatment liquid storage tank 16 into the hydroxyl oxidation chamber 4 to the flow of the treatment liquid into the cathode chamber 2 after passing through the filter device 19 and the soft water device 20 is 2 to 8:1.

[0024] This invention provides a hydroxyl water treatment system based on electrogenerated hydrogen peroxide. In this system, the anode chamber of the hydroxyl water treatment module supports electrolyte recycling. Simultaneously, under the catalytic action of the fiber titanium anode, a large number of protons are generated and enter the cathode chamber. Oxygen from the air enters the cathode chamber through the gas diffusion layer 1051 in the gas diffusion cathode and combines with protons to undergo a two-electron oxygen reduction reaction, converting softened water from the water softening device into a hydrogen peroxide solution (where O2 + 2H+ occurs in the cathode chamber). + +2e - →H2O2 reaction), under the pressure of the second circulation pump 17, enters the hydroxyl oxidation chamber 4 through the pathway, and is irradiated by the microcavity plasma ultraviolet light source to generate hydroxyl free radicals in situ, thereby achieving efficient degradation of pollutants.

[0025] This invention utilizes the excellent oxygen evolution performance of the fiber titanium anode to generate a large number of protons, which are then transported to the cathode. Combined with the structural design of the gas diffusion cathode, it cleverly allows oxygen from the air to react with protons generated on the anode side through the gas diffusion cathode, forming a three-phase reaction interface on the surface of the cathode catalyst (i.e., a heteroatom-doped carbon catalyst layer). This further efficiently generates hydrogen peroxide, which enters the hydroxyl oxidation chamber. Under the catalytic action of broadband ultraviolet light generated by the microcavity plasma ultraviolet light source, a large number of hydroxyl radicals are generated, achieving rapid and efficient degradation of pollutants. This invention utilizes oxygen reduction technology and photocatalysis technology to effectively solve the storage, transportation, and safety issues related to the addition of hydrogen peroxide in traditional advanced oxidation water treatment systems that use hydrogen peroxide as an intermediate. The hydroxyl water treatment system provided by this invention has the advantages of high efficiency, environmental friendliness, wide applicability, and ease of automation.

[0026] The hydroxyl water treatment module of the present invention only requires the addition of readily available supporting electrolyte to the anode chamber. The supporting electrolyte does not participate in the redox reaction and can be recycled. The oxygen required for the oxygen reduction reaction in the cathode chamber can be obtained directly from the air. Softened water can be converted into high-concentration hydrogen peroxide without the need for additional electrolytes, further realizing the efficient degradation of pollutants in the hydroxyl oxidation chamber. It has the advantages of high efficiency and environmental protection, wide applicability, and easy automation.

[0027] Furthermore, this invention involves heteroatom doping of the carbon catalyst layer of the gas diffusion cathode to design a superhydrophobic gas diffusion cathode, which greatly improves the catalytic activity of the oxygen electrochemical reduction reaction to synthesize hydrogen peroxide. By constructing a superhydrophobic catalyst layer surface, the gas affinity of the cathode is enhanced, providing a stable three-phase interface and avoiding the situation where the gas diffusion cathode is flooded with water. This further promotes the effective diffusion and migration of oxygen and ions / molecules, optimizes the mass transfer effect, improves the electrosynthesis capability of hydrogen peroxide, and solves the limitation of electrode catalytic performance caused by the low solubility and diffusivity of oxygen in water. Attached Figure Description

[0028] Figure 1 A schematic diagram of the hydroxyl water treatment system based on electrogenerated hydrogen peroxide provided by the present invention;

[0029] Figure 2 This is a schematic diagram of the hydroxyl water treatment module in the hydroxyl water treatment system provided by the present invention;

[0030] Figure 3 A schematic diagram of the structure of the gas diffusion cathode provided by the present invention;

[0031] Figure 4 This is a graph showing the change of hydrogen peroxide concentration in the cathode cavity with electrolysis time in Embodiment 1 of the present invention;

[0032] Figure 5 This is a test diagram of the hydrophobicity of the gas diffusion cathode catalyst layer in Example 1 of the present invention;

[0033] Figure 6 The image shown is a scanning electron microscope (SEM) image of the fiber titanium anode structure in Example 1 of the present invention; wherein, a is a scanning electron microscope image with an image scale bar of 100 μm, and b is a scanning electron microscope image with an image scale bar of 500 nm.

[0034] Figure 7 This is a schematic diagram of the microcavity plasma ultraviolet light source structure in Embodiment 1 of the present invention;

[0035] Figure 8 This is a spectral test diagram of the microcavity plasma ultraviolet light source in Embodiment 1 of the present invention;

[0036] The components include: 1-hydroxyl water treatment module; 2-cathode cavity; 3-anode cavity; 4-hydroxyl oxidation cavity; 105-gas diffusion cathode; 106-fiber titanium anode; 107-microcavity plasma ultraviolet light source; 121-cathode side plate; 122-first gasket; 123-second gasket; 124-third gasket; 125-proton exchange membrane; 126-fourth gasket; 127-fifth gasket; 128-sixth gasket; 129-isolation plate; 130-seventh gasket; 131-eighth gasket; 132-quartz plate; 133-ninth gasket; 134-light... Source fixing plate; 108-Cathode cavity inlet; 109-Cathode cavity outlet; 110-Anode cavity inlet; 111-Anode cavity outlet; 112-Hydroxyoxidation cavity inlet; 113-Hydroxyoxidation cavity outlet; 14-Anode electrolyte storage tank; 15-First circulation pump; 16-Processed liquid storage tank; 17-Second circulation pump; 18-Diverter; 19-Filter device; 20-Soft water device; 21-Sensor; 22-Regulated DC power supply; 23-Control system; 1051-Gas diffusion layer; 1052-Current collector layer; 1053-Catalyst layer. Detailed Implementation

[0037] like Figures 1-2 As shown, the present invention provides a hydroxyl water treatment system based on electrogenerated hydrogen peroxide, comprising: a hydroxyl water treatment module 1, an anolyte storage tank 14, a first circulation pump 15, a treatment liquid storage tank 16, a second circulation pump 17, a distributor 18, a filter device 19, a water softener 20, a sensor 21, a regulated DC power supply 22, and a control system 23.

[0038] The hydroxyl water treatment module 1, the anolyte storage tank 14 and the first circulation pump 15 are sequentially connected to form an anolyte circulation electrolysis path;

[0039] The hydroxyl water treatment module 1, the treatment liquid storage tank 16, the second circulation pump 17, the distributor 18, the filter device 19 and the soft water device 20 are connected in sequence to form a cathode circulating electrolysis path and a first circulating oxidation path.

[0040] The hydroxyl water treatment module 1, the treatment liquid storage tank 16, the second circulation pump 17 and the distributor 18 are connected in sequence to form the second circulation oxidation path.

[0041] The sensor 21 is installed inside the treatment liquid storage tank 16; the control system 23 is connected to the sensor 21 and the regulated DC power supply 22; the regulated DC power supply 22 is connected to the hydroxyl water treatment module 1;

[0042] The hydroxyl water treatment module 1 includes: a cathode side plate 121, a gas diffusion cathode 105, a cathode cavity 2, a proton exchange membrane 125, an anode cavity 3, a fiber titanium anode 106, an isolation plate 129, a hydroxyl oxidation cavity 4, a quartz plate 132, a light source fixing plate 134, and a microcavity plasma ultraviolet light source 107. All components of the hydroxyl water treatment module 1 are connected by bolts.

[0043] The gas diffusion cathode 105 includes a gas diffusion layer 1051, a current collector layer 1052, and a heteroatom-doped carbon catalyst layer 1053 stacked sequentially.

[0044] In this invention, the treatment liquid in the treatment liquid storage tank 16 is an organic pollution treatment liquid; this invention does not have any special limitations on the source and specific composition of the organic pollution treatment liquid, and any organic pollution treatment liquid known in the art that needs to be treated can be used.

[0045] In a specific embodiment of the present invention, the anolyte in the anolyte storage tank 14 is transported to the inlet 110 of the anode cavity 3 under the action of the first circulation pump 15, flows through the flow channel inside the anode cavity 3, and flows out from the outlet 111 of the anode cavity 3 before returning to the anolyte storage tank 14, and undergoes cyclic electrolysis in sequence. The treatment liquid in the treatment liquid storage tank 16 is partially introduced into the inlet 112 of the hydroxyl oxidation cavity 4 through the diverter 18 under the action of the second circulation pump 17, and the remaining part flows through the filter device 19 and the soft water device 20, and then enters the flow channel inside the cathode cavity 2 through the inlet 108, flows out from the outlet 109 of the cathode cavity 2, and enters the flow channel inside the hydroxyl oxidation cavity 4 through the inlet 112 of the hydroxyl oxidation cavity 4, where the organic pollutants in the treatment liquid are oxidized and decomposed, and then flows back to the treatment liquid storage tank 16 from the outlet 113 of the hydroxyl oxidation cavity 4, and undergoes cyclic oxidation treatment in sequence.

[0046] In a specific embodiment of the present invention, the ratio of the treatment liquid entering the hydroxyl oxidation chamber 4 from the treatment liquid storage tank 16 to the flow into the cathode chamber 2 after passing through the filter device 19 and the soft water device 20 is preferably 2 to 8:1, more preferably 4 to 6:1.

[0047] In a specific embodiment of the present invention, the hydroxyl water treatment module 1 further includes a first washer 122, a second washer 123, a third washer 124, a fourth washer 126, a fifth washer 127, a sixth washer 128, a seventh washer 130, an eighth washer 131, and a ninth washer 133.

[0048] In a specific embodiment of the present invention, the anolyte storage tank 14 is connected to the outlet 111 of the anolyte cavity 3; the first circulation pump 15 is connected to the inlet 110 of the anolyte cavity 3; the treatment liquid storage tank 16 is connected to the outlet 113 of the hydroxyl oxidation cavity 4; the distributor 18 is connected to the inlet 112 of the hydroxyl oxidation cavity 4; the soft water device 20 is connected to the inlet 108 of the cathode cavity 2; and the outlet 109 of the cathode cavity 2 is connected to the inlet 112 of the hydroxyl oxidation cavity 4.

[0049] In a specific embodiment of the present invention, the anolyte in the anolyte storage tank 14 contains an inorganic salt supporting electrolyte, which includes H2SO4, K2SO4, Na2SO4, KNO3 or NaNO3, preferably H2SO4, K2SO4 or Na2SO4, and more preferably Na2SO4. The present invention does not have a special limitation on the concentration of the anolyte, which can be adjusted according to actual needs. Under the anodic catalysis, the anolyte generates a large number of protons in the anolyte cavity 3 (as shown in formula (1)), and enters the cathode cavity 2 through the proton exchange membrane 125 to participate in the oxygen reduction reaction to generate hydrogen peroxide (as shown in formula (2)). Then it enters the hydroxyl oxidation cavity 4, and under the excitation of the microcavity plasma ultraviolet light source 107, generates a large number of hydroxyl radicals in situ (as shown in formula (3)), which efficiently degrade the organic pollutants in the hydroxyl oxidation cavity 4 (as shown in formula (4)).

[0050] H₂O→1 / 2O₂+2H₂ + +2e - (1)

[0051] O2 + 2H + +2e - →H2O2 (2)

[0052] H₂O₂ + hν → 2HO· (3)

[0053] HO· + pollutants → CO2 + H2O (4).

[0054] like Figure 3As shown, the gas diffusion cathode 105 of the present invention comprises a gas diffusion layer 1051, a current collector layer 1052, and a heteroatom-doped carbon catalyst layer 1053 stacked sequentially. The carbon material in the heteroatom-doped carbon catalyst layer is preferably conductive carbon black, graphite, carbon nanotubes, graphene, acetylene black, or activated carbon fiber, preferably conductive carbon black, carbon nanotubes, or graphene, and more preferably conductive carbon black. The heteroatoms preferably include one or more of N, O, and B, preferably co-doped with N and O. The present invention does not impose a special limitation on the doping amount of the heteroatoms; it can be adjusted according to actual needs. The present invention does not impose a special limitation on the doping process of the heteroatoms; heteroatom-doped carbon materials can be prepared by doping according to methods well known in the art, such as chemical vapor deposition, solvothermal methods, or post-processing methods in in-situ synthesis.

[0055] In this invention, the surface contact angle of the heteroatom-doped carbon catalyst layer is preferably 130° to 150°, more preferably 135° to 145°; the present invention preferably mixes the heteroatom-doped carbon material with a PTFE emulsion with a solid content of 60 wt% and performs hydrophobic treatment to obtain the heteroatom-doped carbon catalyst layer; the mass ratio of the heteroatom-doped carbon material to the PTFE emulsion is preferably 1 to 5:1, more preferably 1 to 4:1, and even more preferably 3 to 4:1.

[0056] In this invention, the gas diffusion layer 1051 is preferably made of hydrophobic carbon paper or a hydrophobic PTFE film, more preferably a hydrophobic PTFE film; the current collector layer 1052 is preferably made of stainless steel mesh, titanium mesh, or nickel mesh, more preferably titanium mesh. This invention does not impose any special limitations on the source of the materials for the gas diffusion layer 1051 and the current collector layer 1052; commercially available products well-known in the art are acceptable.

[0057] In this invention, the preferred method for preparing the gas diffusion cathode 105 includes pressing a heteroatom-doped carbon catalyst layer 1053 with a current collector layer 1052 using a hot press, and then hot-pressing the resulting sheet with a gas diffusion layer 1051 to form the gas diffusion cathode 105. The pressing pressure is preferably 10-15 MPa, more preferably 10-12 MPa; the hot-pressing temperature is preferably 80-100°C, more preferably 85-90°C; the pressure is preferably 10-15 MPa, more preferably 12-15 MPa; and the time is preferably 60-300 s, more preferably 90-240 s, and even more preferably 90-180 s.

[0058] In this invention, the proton exchange membrane 125 is preferably a perfluorosulfonic acid proton membrane, and its thickness is preferably 100-250 micrometers, more preferably 120-200 micrometers, and even more preferably 150-200 micrometers.

[0059] In this invention, the substrate of the fiber titanium anode 106 is a fiber titanium felt, the thickness of which is 0.1–0.6 mm, preferably 0.2–0.5 mm, more preferably 0.2–0.4 mm; the porosity is preferably 50–90%, more preferably 60–80%, more preferably 60–70%; the average pore size is preferably 50 μm; a noble metal coating is attached to the surface of the fiber titanium felt, the chemical composition of which is Pt, RuO2, and IrO. 2. IrO2-Ta2O5, RuO2-TiO2, IrO2-TiO2, IrO2-Ta2O5-TiO2, or SnO2-Sb2O5-IrO2, preferably IrO2, IrO2-Ta2O5, IrO2-TiO2, IrO2-Ta2O5-TiO2, or SnO2-Sb2O5-IrO2, more preferably IrO2-Ta2O5-TiO2 or SnO2-Sb2O5-IrO2. This invention does not impose any particular limitation on the specific preparation method of the noble metal coating; any method well-known in the art can be used. This invention also does not impose any particular limitation on the ratio of different metal components in the noble metal coating; adjustments can be made according to actual needs.

[0060] In this invention, the fiber titanium felt is preferably pretreated before use. This invention does not have any special limitations on the pretreatment, and it can be treated according to methods well known in the art.

[0061] In this invention, the cathode side plate 121, the first to ninth washers (122, 123, 124, 126, 127, 128, 130, 131, 133), the anode cavity 3, the cathode cavity 2, and the hydroxyl oxidation cavity 4 in the hydroxyl water treatment module 1 are all provided with square holes of the same cross-sectional size, and the areas of the gas diffusion cathode 105, the proton exchange membrane 125, and the fiber titanium anode 106 are all greater than the area of ​​the square holes, ensuring that the gas diffusion cathode 105, the proton exchange membrane 125, and the fiber titanium anode 106 are completely pressed together in the hydroxyl water treatment module 1.

[0062] The present invention provides a square hole in the cathode side end plate 121 to ensure that the gas diffusion layer 1051 of the gas diffusion electrode 105 is in direct contact with the outside air, so that oxygen in the air can form a three-phase reaction interface on the catalyst surface through the gas diffusion cathode and the protons generated on the anode side, thereby efficiently generating hydrogen peroxide and entering the hydroxyl oxidation chamber 4.

[0063] In this invention, the anode cavity 3, cathode cavity 2 and hydroxyl oxidation cavity 4 in the hydroxyl water treatment module 1 are all made of PMMA, PEEK, PTFE or stainless steel, preferably PEEK or PTFE, and more preferably PEEK; the first gasket to the ninth gasket are all made of PTFE.

[0064] As a specific embodiment of the present invention, the anode cavity 3 is provided with a liquid inlet 110 and a liquid outlet 111, the cathode cavity 2 is provided with a liquid inlet 108 and a liquid outlet 109, and the hydroxyl oxidation cavity 4 is provided with a liquid inlet 112 and a liquid outlet 113. The anode cavity 3, the cathode cavity 2, and the hydroxyl oxidation cavity 4 all contain S-shaped flow channels, and the isolation plate 129 completely isolates the liquid in the anode cavity 3 from the liquid in the hydroxyl oxidation cavity 4.

[0065] In this invention, the transmittance wavelength range of the quartz plate 132 is preferably >185nm, and the transmittance is >90%.

[0066] In this invention, the microcavity plasma ultraviolet light source 107 has a square structure and is fixed within the light source fixing plate 134. The ultraviolet light source wavelength of the microcavity plasma ultraviolet light source 107 is 220–280 nm, and the radiation intensity is preferably 5–10 mW / cm². 2 .

[0067] In this invention, the microcavity plasma ultraviolet light source 107 is composed of a microcavity and a gas chamber filled with rare gas. It has a planar geometry, can be started and stopped instantaneously, has no preheating time, is environmentally friendly (mercury-free), and can generate short wavelengths suitable for the conversion of hydrogen peroxide into hydroxyl radicals. The rare gas is preferably Xe2, KrCl, XeCl, or a phosphor gas.

[0068] In a specific embodiment of the present invention, the sensor 21 is a TOC sensor, and the control system 23 sets the current intensity of the regulated DC power supply 22 according to Equation 1:

[0069]

[0070] In Equation 1, I represents the current intensity of the hydroxyl water treatment module 1, mA·cm. -2 n represents the number of electrons transferred during the complete mineralization of organic pollutants; F represents the Faraday electrolysis constant, 96486 C·mol⁻¹. -1 V represents the volume of the hydroxyl oxidation chamber 4, in L; C TOC This indicates the TOC concentration of organic pollutants, in mg·L⁻¹. -1 4.32×10 7 The conversion factor represents the unit homogenization factor; m represents the number of carbon atoms in the organic pollutant; t represents the electrolysis time, in hours.

[0071] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0072] Example 1

[0073] Pretreatment of titanium mesh: Place the titanium mesh in deionized water and ultrasonically clean it for 20 minutes to remove surface impurities; after ultrasonic cleaning, place the titanium mesh in an 8% NaOH solution and boil for 30 minutes, then remove it and rinse it repeatedly with deionized water several times; after alkaline washing, place the titanium mesh in a 6% oxalic acid solution and boil for 30 minutes, then remove it and rinse it repeatedly with deionized water several times, and air dry it for later use.

[0074] Preparation of nitrogen and oxygen co-doped carbon catalytic materials:

[0075] 5.0 g of conductive carbon black was accurately weighed and dispersed in 50 mL of ethanol. The mixture was ultrasonically treated for 30 min, and then 10.0 g of melamine powder was added and ultrasonic treatment was continued for 90 min. After ultrasonic treatment, the resulting solution was placed in a 90 °C constant temperature water bath until the solution was completely dry. The resulting material was ground into powder and placed in a crucible and then placed in a tubular furnace. In an air environment, the dried mixed powder was first heated to 550 °C at a rate of 5 °C / min and held at that temperature for 60 min, then heated to 850 °C at a rate of 5 °C / min and held at that temperature for 60 min, and then cooled to room temperature at a rate of 5 °C / min to obtain a nitrogen and oxygen co-doped carbon catalytic material.

[0076] Preparation of gas diffusion cathode 105:

[0077] 3.0 g of nitrogen and oxygen co-doped carbon catalyst material was weighed and added to 50 mL of ethanol. The mixture was dispersed with a magnetic stirrer for 20 min. A PTFE suspension with a solid content of 60 wt% was added dropwise to the mixture at a mass ratio of 3:1 between the nitrogen and oxygen co-doped carbon catalyst material and the PTFE emulsion. The mixture was stirred continuously for 2 h. After ultrasonic treatment for 15 min, the mixture was stirred in an 85 °C water bath to form a dough-like carbon catalyst layer. The dough-like carbon catalyst layer was then bonded to a pretreated titanium mesh current collector layer in a hot press at a pressure of 10 MPa to form a sheet. The sheet was then hot-pressed with a gas diffusion layer PTFE hydrophobic film at a pressure of 12 MPa at 90 °C to obtain a gas diffusion cathode 105.

[0078] Preparation of fiber titanium anodes:

[0079] A fiber titanium felt with a thickness of 0.4 mm, a porosity of 70%, and an average pore size of 50 μm was selected as the substrate material. The fiber titanium felt substrate was polished with 1000-grit sandpaper for 10 min. Then, the fiber titanium felt substrate was immersed in 25 wt% NaOH solution for 30 min to remove surface oil. It was washed three times with distilled water, ultrasonicated for 10 min each in acetone, ethanol, and deionized water, and then dried in an oven for 20 min.

[0080] A mixed solution of ethanol and concentrated hydrochloric acid containing 0.4M SnCl4·5H2O, 0.05M SbCl3, and 0.05M IrCl3·H2O was prepared as a solvothermal reaction precursor solution. The precursor solution was added to the polytetrafluoroethylene reaction liner, and a pretreated fiber titanium felt substrate was placed in it. The substrate was then loaded into a hydrothermal reactor and sealed. The reactor was kept at 200℃ for 12 hours. After the reaction was completed, the hydrothermal reactor was cooled to room temperature and removed. The reactor was then annealed in a muffle furnace at 550℃ for 2 hours to obtain the fiber titanium anode SnO2-Sb2O5-IrO2.

[0081] Select a plane size of 5×5cm 2 The effective irradiation area is 16 cm². 2 Microcavity plasma ultraviolet light source, structure as follows Figure 7 As shown;

[0082] The treatment process of a hydroxyl water treatment system:

[0083] An anolyte containing 1 mol / L Na2SO4 as a supporting electrolyte is stored in an anolyte storage tank 14. Under the action of a first circulation pump 15, the anolyte is transported to the anode cavity inlet 110, flows through the flow channel in the anode cavity 3, and flows out from the anode cavity outlet 111 before returning to the anolyte storage tank 14 for cyclic electrolysis. Under the action of a fiber titanium anode with a SnO2-Sb2O5-IrO2 coating on its surface, the anolyte generates a large number of hydrogen ions and then enters the cathode cavity 2 through a proton exchange membrane.

[0084] 100 mL of organic pollutant treatment solution containing 50 mg / L TOC is stored in the treatment solution storage tank 16. Under the action of the second circulation pump 17, after passing through the distributor 18, a portion of the treatment solution enters the hydroxyl oxidation chamber inlet 12, and the remaining portion flows through the filter device 19 and the water softener 20, and then enters the flow channel in the cathode chamber 2 through the cathode chamber inlet 108 of the hydroxyl water treatment module 1. Under the action of the gas diffusion cathode 105, the two-electron reduction reaction of oxygen and hydrogen ions in the cathode chamber produces hydrogen peroxide solution, which then flows out from the cathode chamber outlet 109 and through the hydroxyl oxidation chamber inlet 112. The flow path enters the hydroxyl oxidation chamber 4; the ratio of the organic pollutant treatment liquid in the treatment liquid storage tank 16 entering the hydroxyl oxidation chamber 4 to the liquid flowing through the filter device 19 and the softening water device 20 entering the cathode chamber 2 is 4:1; the mixed solution of hydrogen peroxide and organic pollutants in the hydroxyl oxidation chamber 4, under the action of the microcavity plasma ultraviolet light source 107, converts the hydrogen peroxide in the mixed solution into highly active hydroxyl radicals, efficiently degrading the organic pollutants, and then returns it to the treatment liquid storage tank 16 for 1 hour of cyclic oxidation treatment. The control system 23 adjusts the current intensity of the regulated DC power supply 22 to 40mA / cm. 2 This process completely mineralizes and removes TOC from the organic pollutant treatment solution.

[0085] During the recycling process of organic pollutant treatment liquid, the hydrogen peroxide concentration changes over time as follows: Figure 4 As shown. By Figure 4 It is known that the gas diffusion cathode 105 can effectively utilize oxygen in the air. Under the action of nitrogen and oxygen co-doped carbon catalytic material, it undergoes a two-electron reduction reaction with hydrogen ions in the cathode cavity 2, thereby generating a high-concentration hydrogen peroxide solution in situ with high efficiency. The concentration of the generated hydrogen peroxide solution is >1200mg / L.

[0086] The catalytic layer of the gas diffusion cathode 105 prepared in Example 1 was tested using a contact angle instrument, and the results are as follows: Figure 5 As shown, its contact angle is 142.4°, indicating that it has superhydrophobic properties, which can enhance the gas affinity of the cathode, provide a stable three-phase interface, further promote the effective diffusion and migration of oxygen and ions / molecules, and enhance the mass transfer effect.

[0087] Figure 6 The image shown is a scanning electron microscope (SEM) image of the fiber titanium anode structure in Example 1 of this invention; where a is an SEM image with an image scale bar of 100 μm, and b is an SEM image with an image scale bar of 500 nm; as shown Figure 6 As shown, the fiber titanium felt provides abundant active sites for catalyst loading. After solvent treatment, elliptical SnO2-Sb2O5-IrO2 particles are uniformly loaded onto the surface of the fiber titanium felt substrate, which helps to improve the electrocatalytic performance of the anode.

[0088] Select a plane size of 5×5cm 2 The effective irradiation area is 16 cm². 2 A microcavity plasma ultraviolet light source was constructed, using phosphorescent gas as the filling gas within the chamber. A regulated DC power supply at 12V drove the ultraviolet light source. The spectral characteristics of the ultraviolet light source were detected using a calibrated spectrometer (Ocean Optics USB2000+) and a detector with a spectral range of 200–850 nm. The results are as follows: Figure 8 As shown. By Figure 8 It is known that the microcavity plasma ultraviolet light source has broad spectral characteristics, with a peak wavelength of 226 nm. It can effectively catalyze the oxidation of hydrogen peroxide in the cavity by hydroxyl groups and further efficiently convert it into hydroxyl radicals, thereby achieving efficient degradation of pollutants.

[0089] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydroxyl water treatment system based on electrogenerated hydrogen peroxide, characterized in that, include: Hydroxyl water treatment module (1), anolyte storage tank (14), first circulation pump (15), treatment liquid storage tank (16), second circulation pump (17), distributor (18), filter device (19), soft water device (20), sensor (21), regulated DC power supply (22), control system (23); The hydroxyl water treatment module (1), the anolyte storage tank (14), and the first circulation pump (15) are connected in sequence to form an anolyte circulation electrolysis path; The hydroxyl water treatment module (1), the treatment liquid storage tank (16), the second circulation pump (17), the distributor (18), the filter device (19) and the soft water device (20) are connected in sequence to form a cathode circulating electrolysis path and a first circulating oxidation path. The hydroxyl water treatment module (1), the treatment liquid storage tank (16), the second circulation pump (17) and the distributor (18) are connected in sequence to form a second circulation oxidation path; The sensor (21) is installed inside the treatment liquid storage tank (16); the control system (23) is connected to the sensor (21) and the regulated DC power supply (22); the regulated DC power supply (22) is connected to the hydroxyl water treatment module (1); The hydroxyl water treatment module (1) includes: a cathode side plate (121), a gas diffusion cathode (105), a cathode cavity (2), a proton exchange membrane (125), an anode cavity (3), a fiber titanium anode (106), an isolation plate (129), a hydroxyl oxidation cavity (4), a quartz plate (132), a light source fixing plate (134), and a microcavity plasma ultraviolet light source (107). All components of the hydroxyl water treatment module (1) are connected by bolts. The gas diffusion cathode (105) includes a gas diffusion layer (1051), a current collector layer (1052), and a heteroatom-doped carbon catalyst layer (1053) stacked sequentially. The anolyte in the anolyte storage tank (14) is transported to the inlet of the anode cavity (3) by the first circulation pump (15), and flows out from the outlet of the anode cavity (3) and returns to the anolyte storage tank (14) for cyclic electrolysis. The treatment liquid in the treatment liquid storage tank (16) enters the inlet of the hydroxyl oxidation cavity (4) through the splitter (18) by the second circulation pump (17), and the remaining part flows through the filter device (19) and the soft water device (20) and then enters the flow channel in the cathode cavity (2) through the inlet of the cathode cavity (2). After flowing out from the outlet of the cathode cavity (2), it enters the flow channel in the hydroxyl oxidation cavity (4) through the inlet of the hydroxyl oxidation cavity (4) to oxidize and decompose the organic pollutants in the treatment liquid. Then, it flows back from the outlet of the hydroxyl oxidation cavity (4) to the treatment liquid storage tank (16) for cyclic oxidation treatment. The surface contact angle of the heteroatom-doped carbon catalyst layer is 130°~150°; The substrate of the fiber titanium anode (106) is a fiber titanium felt with a thickness of 0.1~0.6 mm and a porosity of 50~90%. A noble metal coating is attached to the surface of the fiber titanium felt. The chemical composition of the noble metal coating is Pt, RuO2, IrO2, IrO2-Ta2O5, RuO2-TiO2, IrO2-TiO2, IrO2-Ta2O5-TiO2 or SnO2-Sb2O5-IrO2. The microcavity plasma ultraviolet light source (107) has a square structure and is fixed inside the light source fixing plate (134). The ultraviolet light source wavelength of the microcavity plasma ultraviolet light source (107) is 220~280 nm, and the radiation intensity is 5~10 mW / cm². 2 ; The ratio of the flow of the treatment liquid in the treatment liquid storage tank (16) into the hydroxyl oxidation chamber (4) to the flow of the treatment liquid into the cathode chamber (2) after passing through the filter device (19) and the soft water device (20) is 2~8:

1.

2. The hydroxyl water treatment system based on electrogenerated hydrogen peroxide according to claim 1, characterized in that, The hydroxyl water treatment module (1) further includes a first gasket (122), a second gasket (123), a third gasket (124), a fourth gasket (126), a fifth gasket (127), a sixth gasket (128), a seventh gasket (130), an eighth gasket (131), and a ninth gasket (133); The anode chamber (3), cathode chamber (2) and hydroxyl oxidation chamber (4) in the hydroxyl water treatment module (1) are all made of PMMA, PEEK, PTFE or stainless steel; the first gasket to the ninth gasket are all made of PTFE.

3. The hydroxyl water treatment system based on electrogenerated hydrogen peroxide according to claim 1, characterized in that, The anolyte in the anolyte storage tank (14) contains an inorganic salt supporting electrolyte, which includes H2SO4, K2SO4, Na2SO4, KNO3 or NaNO3.

4. The hydroxyl water treatment system based on electrogenerated hydrogen peroxide according to claim 1, characterized in that, The sensor (21) is a TOC sensor, and the control system (23) sets the current intensity of the regulated DC power supply (22) according to Equation 1: Formula 1; In Equation 1, I represents the current intensity of the hydroxyl water treatment module 1, mA. cm -2 n represents the number of electrons transferred during the complete mineralization of organic pollutants; F represents the Faraday electrolysis constant, 96486 C. mol -1 V represents the volume of the hydroxyl oxidation chamber 4, in L; C TOC This indicates the TOC concentration of organic pollutants, in mg. L -1 ; 4.32×10 7 The conversion factor represents the unit homogenization factor; m represents the number of carbon atoms in the organic pollutant; t represents the electrolysis time, in hours.

5. The hydroxyl water treatment system based on electrogenerated hydrogen peroxide according to claim 1, characterized in that, The carbon material in the heteroatom-doped carbon catalyst layer is conductive carbon black, graphite, carbon nanotubes, graphene, acetylene black, or activated carbon fiber, and the heteroatoms include one or more of N, O, and B.

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