A flow type photoelectric integrated in-situ hydrogen peroxide production and synergistic photocatalytic wastewater treatment reactor and treatment method

Abstract

The application discloses a flow type photoelectric integrated in-situ hydrogen peroxide production and wastewater treatment reactor and treatment method. In view of defects of traditional photoelectric Fenton equipment, such as external aeration, high operation energy consumption, low light energy utilization rate and serious hydrogen peroxide loss, the device adopts a carbon nanotube modified self-breathing diffusion cathode, and is matched with a bottom overhead structure to realize in-situ preparation of hydrogen peroxide without aeration. The anode and cathode are compactly arranged, and electrolysis energy consumption is effectively reduced. The photocatalytic membrane assembly is arranged on the top, and a double-mode catalytic system is formed by relying on a dot matrix light source and natural light. Wastewater flows from bottom to top in the reactor, and gas-liquid-solid mass transfer is strengthened by the porous anode, so that in-situ generation of hydrogen peroxide, activation and degradation of organic pollutants are completed in a single device. The application has high integration degree, remarkable energy-saving effect and excellent pollutant degradation efficiency, and can be widely applied to treatment of various types of refractory organic wastewater.

Description

Technical Field

[0001] This invention relates to the field of photoelectric Fenton water treatment technology, specifically to a low-energy wastewater treatment reactor and wastewater treatment method that integrates photoelectric technology to produce hydrogen peroxide in situ and synergistically photocatalyzes. Background Technology

[0002] Photovoltaic Fenton technology is a highly efficient advanced oxidation water treatment technology. With its advantages of generating strong oxidizing reactive oxygen species in situ and its excellent removal effect on recalcitrant organic pollutants, it is widely used in the deep treatment of industrial wastewater and difficult-to-biodegrade organic wastewater. Traditional photovoltaic Fenton water treatment processes typically employ external hydrogen peroxide dosing, independent aeration oxygen supply, and a split photovoltaic reactor structure, which suffers from many problems such as low equipment integration, system complexity, high energy consumption, and expensive reagents.

[0003] Currently, most existing Fenton reactors for producing hydrogen peroxide via electrolysis require continuous oxygen supply from aeration equipment, resulting in high equipment redundancy and high operation and maintenance costs. Furthermore, the conventional electrode arrangement has a large spacing, leading to high resistance between the plates and significant energy loss during electrolysis, resulting in poor economic efficiency in water treatment operations. In addition, the photocatalytic structure of existing photoelectric Fenton reactors is mostly an internal, side-mounted design, relying solely on artificial light sources to complete the catalytic reaction, failing to utilize natural light resources, resulting in low light energy utilization and further increasing the system's operating energy consumption and operating costs.

[0004] Meanwhile, traditional reactors suffer from problems such as separation of hydrogen peroxide generation and catalytic utilization zones, poor wastewater mass transfer, and easy loss and low utilization rate of electrosynthesized hydrogen peroxide, failing to achieve efficient in-situ utilization and thus limiting the degradation efficiency of organic pollutants. Addressing the technical shortcomings of existing photoelectric Fenton water treatment equipment, including high energy consumption, low integration, poor light energy utilization, low hydrogen peroxide utilization, and reliance on aeration equipment, there is an urgent need to develop an integrated photoelectric water treatment reactor and method that is compact, low in energy consumption, can utilize sunlight, requires no additional aeration, and enables in-situ generation and utilization of hydrogen peroxide. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing photoelectric Fenton water treatment technologies, such as low equipment integration, the need for additional aeration, high electrolysis energy consumption, inability to utilize sunlight, low hydrogen peroxide utilization, poor mass transfer, and high operating costs. This invention provides an integrated photoelectric hydrogen peroxide production reactor and wastewater treatment method. The invention aims to achieve an integrated water treatment process that utilizes aeration-free, self-breathing hydrogen peroxide production, low-energy electrolysis, dual-mode catalysis using both sunlight and artificial light sources, and in-situ generation and utilization of hydrogen peroxide. This solves the technical problems of redundant equipment structure, high energy consumption, low light energy utilization, and limited pollutant degradation effects in traditional equipment, thereby improving the treatment efficiency and operational economy of recalcitrant organic wastewater.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] On one hand, this invention provides a flow-type photoelectric integrated reactor for producing hydrogen peroxide and its catalytic utilization, including a reactor body and a dot matrix light source. The reactor body includes a reactor shell, and a cathode, anode, and photocatalytic membrane assembly arranged inside the shell; wherein, the cathode is a carbon nanotube-modified self-breathing diffusion cathode, possessing excellent oxygen permeation and reduction performance, achieving autonomous oxygen supply without external aeration equipment. The cathode and anode adopt a close-range compact arrangement structure, effectively reducing the resistance between the plates, reducing energy loss during electrolysis, and achieving low-energy operation.

[0008] The photocatalytic membrane assembly consists of a glass fiber plate and a photocatalyst supported on the surface of the glass fiber plate. It is positioned at the top of the reactor's inner shell, with a quartz glass window at the top allowing ample natural light to be received, providing structural conditions for direct sunlight participation in the catalytic reaction and overcoming the limitations of traditional devices that rely solely on artificial light sources. The reactor shell, in conjunction with a gasket, elevates the bottom of the reactor shell, ensuring dynamic and stable airflow at the bottom of the carbon nanotube-modified self-breathing diffusion cathode, thus guaranteeing the continuous and efficient electrosynthesis of hydrogen peroxide.

[0009] The feeding unit includes a liquid inlet pump for stably supplying wastewater to the reactor. The dot matrix light source is positioned corresponding to the top photocatalytic membrane assembly, providing stable excitation light energy to activate the photocatalyst and hydrogen peroxide. This, combined with sunlight, achieves a dual catalytic mode of artificial and natural light, ensuring efficient and all-weather oxidation reaction. The reactor interior features a bottom-up water flow channel. As the wastewater flows through the porous anode, the liquid phase components and pollutants continuously and dynamically change, effectively enhancing the gas-liquid-solid three-phase mass transfer effect.

[0010] On the other hand, the present invention provides a wastewater treatment method based on the above-mentioned reactor, comprising the following steps: pumping the wastewater to be treated into the reactor through the inlet between the cathode and the anode using an inlet pump; applying voltage to the carbon nanotube modified self-breathing diffusion cathode and the anode, and relying on the bottom overhead structure to enable air to autonomously enter the cathode surface, thus achieving in-situ electrosynthesis of hydrogen peroxide without aeration; the wastewater permeates and flows from bottom to top, continuously renewing the reaction interface and enhancing mass transfer efficiency; the wastewater containing hydrogen peroxide is transported to the photocatalytic membrane area at the top of the reactor, where the photocatalyst is activated by supplemental lighting with a lattice light source or by directly using sunlight to generate a large number of active oxygen species, which efficiently degrade organic pollutants in the wastewater through photoelectro-Fenton reaction; and finally, the treated wastewater is discharged from the outlet, realizing in-situ generation and efficient utilization of hydrogen peroxide.

[0011] Compared with the prior art, the present invention has the following significant advantages:

[0012] (1) This invention uses a carbon nanotube-modified self-breathing diffusion cathode, combined with an overhead structure at the bottom of the reactor, to achieve autonomous air circulation and oxygen supply, eliminating the need for aeration equipment in traditional processes, simplifying the system structure, reducing equipment investment and subsequent operation and maintenance costs, and achieving efficient electrosynthesis of hydrogen peroxide without aeration. Without an overhead ventilation structure at the bottom, the carbon nanotube cathode cannot circulate air continuously, and the self-breathing oxygen supply fails; with only an overhead structure at the bottom, the oxygen reduction selectivity of ordinary cathodes is poor, resulting in low hydrogen peroxide production. The combination of the two achieves in-situ hydrogen peroxide production without aeration, eliminating the need for traditional aeration equipment at the source, and achieving synergistic innovation in structure and materials.

[0013] (2) This invention adopts a compact arrangement of the anode and cathode at close range, which effectively reduces the contact resistance between the plates and significantly reduces the energy consumption of electrolysis. This solves the problems of high energy consumption and poor economic efficiency of traditional photoelectric Fenton devices, and significantly improves the energy efficiency of water treatment. Meanwhile, the low energy consumption condition also ensures the oxygen reduction stability of the carbon nanotube cathode, avoiding the problems of electrode polarization and increased side reactions caused by high voltage. The two features complement each other and work together to achieve "low-energy hydrogen peroxide production".

[0014] (3) This invention places the photocatalytic membrane module on top, which has a reasonable structure and good light-gathering effect. It can achieve stable artificial photocatalytic reaction by relying on the array light source, and can make full use of solar resources to realize dual-mode operation of photocatalysis, effectively improving the light energy utilization rate and further reducing the system's operating energy consumption. The photocatalytic membrane is placed on top to match the natural light collection, and the array light source serves as supplementary light; while the bottom-up flow field precisely delivers high-concentration hydrogen peroxide to the top photocatalytic zone, realizing the continuous completion of the entire process of hydrogen peroxide production → hydrogen peroxide activation → pollutant degradation in a single reactor. The electrosynthetic products are seamlessly connected with the photocatalytic unit, completely solving the traditional problem of "separation of production and use, and hydrogen peroxide loss".

[0015] (4) The present invention adopts a bottom-up penetrating flow mode, combined with the structural characteristics of porous anode, which can realize the dynamic renewal of wastewater components and enhance the mass transfer efficiency of the three-phase interface; at the same time, hydrogen peroxide electrosynthesis and photocatalytic Fenton oxidation are coupled in a single reactor to realize the in-situ generation and utilization of hydrogen peroxide, avoid local accumulation and decomposition loss of hydrogen peroxide, and greatly improve the utilization rate of hydrogen peroxide and the degradation efficiency of organic pollutants.

[0016] (5) The overall energy consumption of this invention is significantly reduced. First-level energy saving: the self-breathing cathode and the bottom-mounted design eliminate the need for aeration equipment, reducing aeration energy consumption and equipment costs; second-level energy saving: the compact electrode arrangement reduces electrolysis resistance, thus lowering electrolysis energy consumption; third-level energy saving: the top-mounted structure utilizes natural light, reducing the power consumption of artificial light sources. With these three elements working in tandem, the unit water treatment energy consumption is reduced by more than 35% compared to traditional processes. Traditional technologies cannot achieve this comprehensive energy-saving effect by optimizing only one aspect (such as simply changing the electrodes or adding natural light).

[0017] (6) This invention achieves a synergistic gain of 1+1>2, resulting in a significant improvement in hydrogen peroxide utilization. In traditional separate devices, the electro-generated hydrogen peroxide region and the photocatalytic region are separated, leading to high transmission losses and hydrogen peroxide utilization rates generally below 50%; hydrogen peroxide accumulates in large quantities under light-free conditions. The coupling effect of this patent is: in-situ integrated production and utilization + enhanced mass transfer + photoelectric synergistic activation, increasing hydrogen peroxide utilization to over 85% with no obvious residue, representing a new effect after coupling.

[0018] (7) The device of the present invention has high integration, compact structure and stable operation. It can be adapted to the deep treatment of various types of recalcitrant organic wastewater. It has the advantages of low cost, low energy consumption, high efficiency and green energy saving, and has good engineering application and promotion value. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the photoelectric integrated hydrogen peroxide production and catalytic utilization reaction device of the present invention;

[0020] Figure 2 This is a schematic diagram of the main reactor for the photoelectric integrated hydrogen peroxide production and catalytic utilization of the present invention;

[0021] Figure 3 This is a schematic cross-sectional view of the main reactor for the photoelectric integrated hydrogen peroxide production and catalytic utilization of the present invention;

[0022] Figure 4 This is a schematic diagram of a porous anode.

[0023] Figure 5 This is a schematic diagram of a self-breathing air cathode loaded with carbon nanotubes. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0025] This invention discloses a flow-type photoelectric integrated hydrogen peroxide production reactor and its catalytic utilization, as well as a wastewater treatment method. The core innovations are: using a carbon nanotube-modified self-breathing diffusion cathode in conjunction with a bottom-mounted structure to achieve in-situ hydrogen peroxide production without aeration; reducing electrolysis energy consumption through close and compact arrangement of the anode and cathode; placing the photocatalytic membrane module at the top to achieve dual-mode catalysis using sunlight and artificial dot matrix light sources; and combining dynamic mass transfer of porous anodes with a bottom-up penetrating flow field design to complete in-situ hydrogen peroxide generation, in-situ activation and utilization, and efficient degradation of organic pollutants in a single reactor. This effectively solves the technical pain points of traditional photoelectric Fenton technology, such as high energy consumption, complex equipment, low light energy utilization, large hydrogen peroxide loss, and limited treatment effect.

[0026] Figure 1This is a schematic diagram of the photoelectric integrated hydrogen peroxide production and catalytic utilization reaction device of the present invention. To illustrate the device more clearly, [the diagram is shown below]. Figure 2 A schematic diagram of the main reactor for the photoelectric integrated hydrogen peroxide production and catalytic utilization of this invention is shown. Figure 3 This invention presents a schematic cross-sectional view of the main reactor for the photoelectric integrated hydrogen peroxide production and catalytic utilization.

[0027] The reactor structure of this invention includes a reactor body, a feeding unit, a dot matrix light source, and a DC power supply. The reactor body consists of an annular baffle 1 at the bottom of the reactor, a quartz glass plate 2, a cathode 3, an anode 4, and a photocatalytic membrane assembly. The cathode is a carbon nanotube-modified self-breathing diffusion cathode, possessing excellent gas permeability and electrocatalytic reduction activity, and can directly utilize freely flowing oxygen from the air as the reaction gas source. The cathode and anode are powered by a DC power supply 9. The anode and cathode are arranged in a close-proximity, compact manner, significantly reducing the distance between the plates, effectively lowering the contact resistance between the plates, reducing energy loss during electrolysis, and achieving a low-energy electrolysis reaction.

[0028] A pad 12 is installed at the bottom of the reactor shell. The entire reactor shell is suspended by the pad, which creates an open ventilation channel at the bottom of the carbon nanotube modified self-breathing diffusion cathode. Air can naturally, continuously and stably circulate and diffuse to the cathode reaction interface. There is no need for external aeration fans, aeration pipes and other auxiliary oxygen supply equipment. The self-breathing method of air can continuously provide sufficient oxygen for the electrosynthesis of hydrogen peroxide reaction, which greatly simplifies the equipment system structure and reduces equipment investment and daily operation and maintenance costs.

[0029] The photocatalytic membrane module consists of a glass fiber plate 6 and a photocatalyst 5 uniformly loaded on the surface of the glass fiber plate, and is fixedly installed at the top of the inner shell of the reactor. The top-mounted structure is unobstructed and has excellent lighting conditions. On the one hand, it can directly receive sunlight as the light source for the catalytic reaction under sufficient natural light conditions, making full use of clean energy and reducing the energy consumption of artificial light sources. On the other hand, the corresponding dot matrix light source 10 at the top position can provide stable and uniform excitation light energy in scenarios with insufficient light, such as at night and on cloudy or rainy days, to ensure that the photocatalyst continuously activates hydrogen peroxide, achieves stable operation in all weather conditions, and effectively broadens the applicable scenarios of the equipment.

[0030] The reactor's inner shell sidewall has an inlet 7 and an outlet 8. Inlet 7 is located between the cathode 3 and the anode 4, closer to the cathode 3. Outlet 8 is located between the anode 4 and the top photocatalytic membrane assembly, closer to the photocatalytic membrane assembly, forming a stable, bottom-to-top permeable water flow path. The anode employs a porous structure. As wastewater flows upward through the porous anode region driven by the pump, pollutants, dissolved oxygen, and trace liquid components in the water continuously and dynamically change, effectively renewing the gas-liquid-solid three-phase reaction interface, significantly enhancing the system's mass transfer efficiency, preventing the accumulation of reaction products, and ensuring the continuous and efficient electrolysis of hydrogen peroxide.

[0031] The feeding unit mainly includes a liquid inlet pump 11 and supporting pipelines. The liquid inlet pump precisely controls the flow rate of wastewater, ensuring stable and uniform water flow in the reactor, providing stable water inlet conditions for continuous water treatment operations, and adapting to large-scale and continuous wastewater treatment conditions.

[0032] The specific implementation process of wastewater treatment based on the above reactor is as follows: When the equipment is running, start the inlet pump and pump the recalcitrant organic wastewater to be treated into the bottom area of ​​the reactor shell at a constant speed through the inlet; then apply a constant voltage or constant current to the carbon nanotube modified self-breathing diffusion cathode and anode, and use the bottom-mounted ventilation structure to allow air to diffuse autonomously to the cathode surface, where oxygen undergoes an electro-reduction reaction and hydrogen peroxide is continuously generated in situ.

[0033] Driven by the water flow, the wastewater containing in-situ generated hydrogen peroxide flows steadily from bottom to top along the fixed flow channel, continuously scouring the surface of the porous anode, constantly renewing the reaction interface, and further improving mass transfer and reaction efficiency. At the same time, thanks to the close-range arrangement of the anode and cathode, the ineffective energy consumption of the electrolysis process is greatly reduced, and the overall water treatment operation energy consumption is significantly reduced.

[0034] Finally, the hydrogen peroxide-containing wastewater is smoothly transported to the photocatalytic membrane module area at the top of the reactor. The operating mode is selected according to the ambient light conditions: when there is sufficient natural light, the photocatalyst is directly excited by sunlight; when there is insufficient light, a lattice light source is turned on to provide auxiliary light energy. The photocatalyst exhibits excellent catalytic activity under light energy excitation, which can efficiently activate the hydrogen peroxide generated in situ within the system, producing a large number of highly oxidizing reactive oxygen species such as hydroxyl radicals and superoxide radicals. Through photoelectric synergistic Fenton oxidation, it rapidly oxidizes and decomposes the recalcitrant organic pollutants in the wastewater, achieving efficient removal of pollutants.

[0035] After thorough oxidation and degradation, the clean wastewater is finally discharged stably from the outlet. The entire process realizes in-situ generation, in-situ activation, and in-situ utilization of hydrogen peroxide, completely avoiding the reagent loss and waste caused by the addition of hydrogen peroxide and long-distance transportation of hydrogen peroxide in traditional processes, and greatly improving the utilization efficiency of hydrogen peroxide and the wastewater treatment effect.

[0036] This invention effectively integrates the advantages of electrosynthetic hydrogen peroxide and photoelectric Fenton catalytic oxidation technologies through its integrated structure, lightweight energy consumption, dual-mode light source, and in-situ reaction design. The equipment is compact, requires no aeration, has low energy consumption, high light energy utilization, and stable treatment effect. It can be effectively applied to the deep treatment of various recalcitrant organic wastewaters such as dyeing and printing wastewater, chemical wastewater, and pharmaceutical wastewater, and has strong engineering practicality and market promotion value.

[0037] Example 1: Experiment on the effect of different types of carbon nanotubes on reactor performance

[0038] In this embodiment, the fixed electrode spacing is 10 mm, the influent flow rate is 10 mL / min, and the current density is 10 mA / cm². 2 0.1 mol / L Na₂SO₄ was used as the supporting electrolyte. Only the type of carbon nanotubes used for cathode modification was adjusted, with concentrations of 0.5 mg / cm⁻¹ being selected. 2 Multi-walled carbon nanotubes, commercial C3N4, and activated carbon were used to modify and load diffusion cathodes in equal amounts to investigate the effects of different carbon nanotube structures on the H2O2 production performance and water treatment effect of the self-breathing cathode.

[0039] Experimental results show that multi-walled carbon nanotube-modified cathodes have uniform diameters, moderate defect sites, and the best oxygen reduction selectivity, achieving a steady-state H2O2 concentration of 1000-1100 mg / L. Commercially available C3N4-modified cathodes produce a steady-state H2O2 concentration of 500-600 mg / L. Activated carbon exhibits the worst hydrogen peroxide production efficiency, with a steady-state H2O2 concentration of only 300-400 mg / L, comparable to the H2O2 production efficiency of unsupported cathodes. Therefore, multi-walled carbon nanotubes are determined to be the optimal modification material for this reactor, possessing excellent electrical conductivity, oxygen permeability, and catalytic selectivity.

[0040] Example 2: Experiment on Gradient Optimization of Anode-Cathode Plate Spacing

[0041] This embodiment maintains all optimal structural and process parameters: carbon nanotube modified cathode (loading 0.5 mg / cm²). 2 ), current density 10 mA / cm 2 The influent flow rate is 10 mL / min, treating wastewater initially containing 20 mg / L tetracycline (containing 0.1 mol / L Na2SO4). In this embodiment, four sets of anode and cathode plate spacing gradients of 5 mm, 10 mm, 15 mm, and 20 mm are set as single variables.

[0042] The operational results show that when the electrode spacing is 5 mm, the electrode distance is too small, resulting in narrow water flow channels, high water flow resistance, and the potential for stagnant water and material accumulation in certain areas. This hinders gas-liquid-solid mass transfer, causes uneven current distribution between the electrodes, and slight electrode polarization. While energy consumption is low, the flow channels are prone to blockage. With a electrode spacing of 10 mm, the flow channels are unobstructed, the resistance between the electrodes is minimal, the current distribution is uniform, there is no polarization or water flow obstruction, and the overall energy consumption is the lowest. With a electrode spacing of 15 mm, the resistance between the electrodes gradually increases, leading to increased ineffective energy consumption during electrolysis and an increase in side reactions. With a electrode spacing of 20 mm, the electrode spacing is too large, resulting in a significant increase in resistance, a substantial increase in electrolysis energy consumption, exacerbated oxygen reduction side reactions, and a decrease in H2O2 selectivity. Therefore, setting the electrode spacing to 10 mm is the optimal value for this device, balancing low resistance, low electrolysis energy consumption, unobstructed flow channels, and efficient mass transfer; it represents the optimal parameter matching value.

[0043] Example 3: Current Density Gradient Optimization Experiment

[0044] This embodiment maintains all optimal structural and process parameters: carbon nanotube modified cathode (loading 0.5 mg / cm²). 2 The anode-cathode spacing was 10 mm, and the influent flow rate was 10 mL / min, treating wastewater initially containing 20 mg / L tetracycline (containing 0.1 mol / L Na₂SO₄). This embodiment was set at 5 mA / cm². 2 10 mA / cm 2 15 mA / cm 2 20 mA / cm 2 The four sets of current density gradients are single variables.

[0045] The operating results show that the current density is 5 mA / cm². 2 The electrolysis reaction lacks sufficient driving force, resulting in a slow oxygen reduction reaction rate, low H2O2 production, and insufficient capacity to meet the wastewater treatment load. Current density: 10 mA / cm² 2 The electrocatalytic reaction rate is perfectly matched with the oxygen supply and mass transfer rate, achieving the highest selectivity for H2O2 formation, minimal side reactions, and an optimal balance between energy consumption and yield. Current density: 15 mA / cm² 2 When the driving force of the reaction is excessive, oxygen evolution and hydrogen evolution side reactions occur at the cathode, the oxygen reduction selectivity decreases, and energy consumption increases. Current density 20 mA / cm² 2 High current at high currents induces severe electrode polarization and numerous side reactions, leading to decreased stability of the carbon nanotube cathode, localized overheating, and a surge in energy consumption. Long-term operation can easily damage the electrode. Therefore, a current of 10 mA / cm² was chosen. 2 To achieve the optimal current density, this parameter is matched with the oxygen supply capacity of the self-breathing cathode, the bottom ventilation volume, and the height of the electrode spacing, ensuring high H2O2 production while suppressing side reactions and controlling energy consumption.

[0046] Example 4: Influent flux (flow rate) gradient optimization experiment

[0047] This embodiment maintains all optimal structural and process parameters: carbon nanotube modified cathode (loading 0.5 mg / cm²). 2 Anode-cathode spacing 10 mm, current density 10 mA / cm² 2 The initial 20 mg / L tetracycline (containing 0.1 mol / L Na2SO4) wastewater was treated. In this embodiment, three gradients of influent flux of 5 mL / min, 10 mL / min, and 15 mL / min were set as single variables.

[0048] The operational results show that: at an influent flux of 5 mL / min, the water flow rate is too slow, resulting in a low rate of interface renewal from bottom to top, weakened gas-liquid-solid three-phase mass transfer, and localized accumulation of H2O2 in the electrolysis zone, leading to premature decomposition and loss. At an influent flux of 10 mL / min, the water flow rate precisely matches the H2O2 production rate and photocatalytic activation rate, ensuring continuous dynamic renewal of the reaction interface. H2O2 is smoothly transported from the electrolysis zone to the top photocatalytic zone without localized accumulation, achieving optimal mass transfer efficiency. At an influent flux of 15 mL / min, the water flow rate is too fast, resulting in insufficient residence time of wastewater in the electrolysis and photocatalytic zones. H2O2 is not fully generated and activated before flowing out, leaving residual H2O2 in the effluent. Therefore, 10 mL / min is the optimal influent flux. This flow rate is well-suited to the device cavity size, the mass transfer characteristics of the porous anode, and the reaction time of the top photocatalytic zone, achieving a complete matching of the production, transport, and catalytic processes.

[0049] Example 5: Experiment on Gradient Optimization of Carbon Nanotube Loading

[0050] In this embodiment, all optimal structural and process parameters are fixed: anode-cathode spacing 10 mm, current density 10 mA / cm². 2 The influent flux was 10 mL / min, treating wastewater initially containing 20 mg / L tetracycline (containing 0.1 mol / L Na₂SO₄). In this embodiment, the multi-walled carbon nanotube loading was set at 0.2 mg / cm². 2 0.5 mg / cm 2 0.8 mg / cm 2 The three gradients are all single variables.

[0051] The operating results show that the loading capacity is 0.2 mg / cm³. 2 The cathode surface lacks sufficient catalytic active sites, resulting in weak oxygen reduction and low H2O2 yield. Loading capacity: 0.5 mg / cm³ 2 The number of active sites, carbon nanotube film thickness, and gas permeability reach a balance, resulting in smooth oxygen permeation and the strongest catalytic selectivity. Loading capacity: 0.8 mg / cm³ 2When the membrane layer is too thick, the resistance to air permeation at the cathode increases, the efficiency of self-respiration oxygen supply decreases, and the oxygen supply is insufficient. Therefore, 0.5 mg / cm 2 The optimal loading of carbon nanotubes is achieved, balancing catalytic activity and gas permeability.

[0052] Example 6: Comparative Experiment on Pollutant Removal Efficiency and Reaction Performance with and without Light Irradiation

[0053] This embodiment maintains all optimal structural and process parameters: carbon nanotube modified cathode (loading 0.5 mg / cm²). 2 Anode-cathode spacing 10 mm, current density 10 mA / cm² 2 The influent flow rate was 10 mL / min, treating wastewater initially containing 20 mg / L tetracycline (containing 0.1 mol / L Na2SO4). In this embodiment, only the illumination condition was set as a single variable, with two control groups: the experimental group had illumination (a dot matrix light source), while the control group had the light source completely blocked, retaining only the electrocatalytic reaction without photocatalytic activation. The differences in hydrogen peroxide utilization, free radical generation level, and pollutant removal efficiency between the two systems were compared.

[0054] Experimental results show that under conditions of no light and only electrocatalysis, the reactor relies solely on electrochemical action to degrade pollutants. Hydrogen peroxide is continuously generated at the cathode, but it cannot be efficiently activated and converted. A large amount of H2O2 accumulates in the system, with extremely low utilization. The steady-state residual H2O2 concentration can reach 900-1000 mg / L, but the production of reactive oxygen free radicals is low, the degradation capacity of organic pollutants is limited, the TC removal rate is only 35%-40%, and a large amount of unused hydrogen peroxide remains in the effluent, resulting in serious resource waste.

[0055] Under photoelectric synergy with illumination, the top-mounted photocatalytic membrane module fully receives light energy, effectively activating the photocatalyst (MnO2 catalyst used in this experiment). This rapidly and continuously activates the in-situ generated hydrogen peroxide, efficiently converting H2O2 into highly reactive singlet oxygen, hydroxyl radicals, superoxide radicals, and other reactive oxygen species, significantly enhancing the oxidative degradation capacity. Under illumination, the system's hydrogen peroxide utilization rate increases to over 85%, with no significant hydrogen peroxide residue, and the TC removal rate increases to 98%-100%. Compared to a lightless pure electrolysis system, the pollutant removal efficiency is improved by approximately 60 percentage points.

[0056] This embodiment fully demonstrates that the top photocatalytic structure and photoelectric coupling design of the present invention are not simply superimposed, but achieve a highly efficient match between electrogenerated hydrogen peroxide and photocatalytic activation, significantly improving the utilization rate of hydrogen peroxide and the ability to degrade pollutants, highlighting the core innovation and technological superiority of the top-mounted photocatalytic membrane + solar energy utilization + photoelectric integrated coupling.

[0057] Example 7: Long-term stable operation experiment

[0058] This embodiment integrates optimal process parameters: carbon nanotube modified cathode, loading content 0.5 mg / cm³. 2 Current density 10 mA / cm 2 The reactor was designed with an influent flux of 10 mL / min, an anode-cathode spacing of 10 mm, and operated under a self-breathing, non-aeration condition, utilizing a dual-mode synergistic catalysis system of sunlight and a lattice light source. A continuous 72-hour long-term stable operation experiment was conducted to monitor the reactor's hydrogen peroxide production performance and pollutant degradation stability.

[0059] The operational results show that the device operates smoothly throughout the entire process, with no electrode polarization, no material shedding, and no blockage. The H2O2 concentration in the system remains stable at 1000-1100 mg / L for a long period, and energy consumption shows no significant upward trend. This demonstrates that by optimizing the carbon nanotube modification parameters and electrical and hydraulic conditions, this invention can achieve long-term, efficient, low-energy-consumption, and stable operation, exhibiting strong engineering reliability.

[0060] Comparative Example: Control Experiment of Traditional Process Reactor

[0061] A conventional split-type photoelectric Fenton reactor was used, employing ordinary carbon electrodes, a wide-spacing electrode structure, external aeration for oxygen supply, and a side-mounted artificial light source. Comparative tests were conducted under the same water quality, optimal hydraulic retention time, and electrical parameters. The results showed that the conventional reactor, lacking a carbon nanotube-modified self-breathing structure, required continuous aeration for oxygen supply, significantly increasing energy consumption. Furthermore, the electrode catalytic selectivity was poor, with numerous side reactions; H2O2 production was only about 60% of the optimal operating conditions of this invention; it could not utilize sunlight, resulting in low light energy utilization; hydrogen peroxide loss was high; and mass transfer was poor. The energy consumption per unit of water treated was more than 35% higher than that of this invention, making its overall treatment performance and economic efficiency far inferior.

[0062] In summary, this invention combines material modification, low-energy electrode structure, and process parameter optimization to achieve in-situ generation and efficient utilization of hydrogen peroxide under aeration-free conditions. It effectively overcomes the drawbacks of traditional photoelectric Fenton technology, such as high energy consumption, low light energy utilization, hydrogen peroxide waste, and poor mass transfer. The equipment has excellent processing performance, stable operation, and outstanding energy efficiency, and has good engineering application and promotion value.

Claims

1. A flow-type photoelectric integrated hydrogen peroxide production reactor and its catalytic utilization reactor, characterized in that, It includes the reactor body, feeding unit (7), water outlet unit (8), power supply (9) and dot matrix light source (10); The reactor body includes a reactor shell, and a cathode (3), an anode (4) and a photocatalytic membrane assembly disposed within the reactor shell; the photocatalytic membrane assembly includes a glass fiber plate (6) and a photocatalyst (5) loaded on the surface of the glass fiber plate, and a quartz glass plate (2) is provided on the top of the reactor. The cathode is a carbon nanotube-modified self-breathing diffusion cathode, and the cathode and anode are arranged in close proximity to each other. The photocatalytic membrane assembly is fixedly installed in the upper region of the reactor shell; The bottom of the reactor shell has an annular partition (1) and is supported by a pad (12), so that the reactor shell is completely suspended. The feeding unit includes a liquid inlet pump (11), which is connected to the inside of the reactor shell.

2. The flow-type photoelectric integrated hydrogen peroxide production reactor and its catalytic utilization reactor according to claim 1, characterized in that, The anode has a porous structure; a bottom-up penetrating water flow path is formed inside the reactor shell.

3. The flow-type photoelectric integrated hydrogen peroxide production reactor and its catalytic utilization reactor according to claim 1, characterized in that, The distance between the cathode and anode plates is 5 mm to 25 mm.

4. The flow-type photoelectric integrated hydrogen peroxide production reactor and its catalytic utilization reactor according to claim 1, characterized in that, The carbon nanotubes in the self-breathing diffusion cathode are multi-walled carbon nanotubes; the loading of the multi-walled carbon nanotubes on the cathode surface is 0.2 mg / cm². 2 -0.8 mg / cm 2 .

5. The flow-type photoelectric integrated hydrogen peroxide production reactor and its catalytic utilization reactor according to claim 1, characterized in that, The pad creates an open ventilation channel at the bottom of the reactor shell, allowing air to circulate to the bottom surface of the carbon nanotube-modified self-breathing diffusion cathode.

6. The flow-type photoelectric integrated hydrogen peroxide production reactor and its catalytic utilization reactor according to claim 1, characterized in that, The reactor shell is provided with a quartz glass window at the top, through which the photocatalytic membrane module receives natural light, forming a dual-light source catalytic system with the dot matrix light source.

7. A wastewater treatment method based on the reactor according to any one of claims 1-6, characterized in that, Includes the following steps: S1: The wastewater to be treated is pumped from the inlet to the bottom of the reactor shell by the inlet pump; S2: Apply voltage or current to the cathode and anode, and introduce air using the overhead structure at the bottom of the reactor shell to generate hydrogen peroxide in situ on the cathode surface; S3: Wastewater containing hydrogen peroxide flows upward along a bottom-up water flow path; S4: Wastewater flows through the upper photocatalytic membrane module area, where the photocatalyst is excited by a dot matrix light source or sunlight to activate hydrogen peroxide and degrade organic pollutants in the wastewater. S5: The wastewater after degradation is completed is discharged from the outlet.

8. The wastewater treatment method according to claim 7, characterized in that, The applied current density is 5 mA / cm². 2 -20 mA / cm 2 .

9. The wastewater treatment method according to claim 7, characterized in that, The inlet pump controls the inlet water flow rate to be 5 mL / min-15 mL / min.

10. The wastewater treatment method according to claim 7, characterized in that, This method completes the coupled reaction of hydrogen peroxide electrosynthesis and hydrogen peroxide photocatalytic Fenton oxidation within the same reactor.

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