Electro-Fenton permeable reactive barrier system and application

Abstract

The invention provides an electro-Fenton permeable reactive barrier system and application. The electro-Fenton permeable reactive barrier system comprises a permeable reactive barrier main body, an electro-Fenton reaction unit, a solid electrolyte layer and a photovoltaic energy unit, and is electrically connected with the electro-Fenton reaction unit, so that the fundamental problems that the degradation efficiency of refractory organic matters such as antibiotics is low and a filling medium is easy to inactivate in the traditional PRB technology are solved. Energy self-sufficiency and all-weather stable operation of the system in an underground water environment are achieved, dependence on power supply of a power grid is eliminated through the integrated photovoltaic-energy storage unit, and the limitation that a traditional electro-Fenton technology is difficult to apply to remote sites is overcome. The invention further provides application of the electro-Fenton permeable reactive barrier system to in-situ remediation of groundwater pollution.

Description

Technical Field

[0001] This invention belongs to the field of in-situ remediation technology for groundwater pollution, specifically relating to an electro-Fenton infiltration reactive barrier system and its application. Background Technology

[0002] Groundwater, as a core resource for maintaining ecological balance and ensuring drinking water safety, is of paramount importance in terms of its quality. However, groundwater pollution is becoming increasingly severe, with pollution sources exhibiting diversified and complex characteristics. Wastewater discharged from industries such as pharmaceuticals, chemicals, and livestock farming carries large amounts of antibiotics, endocrine disruptors, and other persistent organic pollutants. After seepage or substandard discharge into aquifers, these pollutants, due to their persistence and high biological activity, remain in groundwater for extended periods. This not only induces the development of antibiotic-resistant genes in microorganisms but may also accumulate through the food chain, threatening human health. Petroleum hydrocarbons, through leakage during storage and transportation, pollute groundwater; components such as benzene and polycyclic aromatic hydrocarbons pose carcinogenic, teratogenic, and mutagenic risks. Excessive use of fertilizers and pesticides in agricultural production, along with improper disposal of livestock manure, leads to the leaching of nitrogen and phosphorus nutrients and organochlorine pesticides into groundwater, creating large-scale non-point source pollution. These pollutants migrate and accumulate in groundwater, posing a significant and long-term hidden risk to ecosystems and public health. Therefore, how to overcome the technical bottlenecks such as low electrical conductivity of groundwater, limited energy supply, and insufficient stability of catalytic systems, and develop a new integrated remediation technology that is energy-sufficient, highly efficient, stable, green, and environmentally friendly, to achieve the complete removal of antibiotics and other recalcitrant organic pollutants from groundwater, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0003] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides an electro-Fenton osmosis reactive barrier system, suitable for the efficient and continuous degradation of organic pollutants such as antibiotics in groundwater with poor conductivity, achieving energy self-sufficiency and all-weather operation.

[0004] This invention also provides the application of the electro-Fenton permeable reactive barrier system in in-situ remediation of groundwater pollution.

[0005] Permeable Reactive Barrier (PRB) technology is an in-situ groundwater remediation method. It involves constructing a passive reaction zone filled with active media along the path of a contaminated plume. Utilizing the natural hydraulic gradient, groundwater flows through this zone, where pollutants are fixed or transformed through reduction and adsorption. However, this technology has significant limitations when treating recalcitrant organic pollutants such as antibiotics: the PRB is often anoxic or hypoxic environment, and the reaction relies on chemical reduction pathways, resulting in low pollutant degradation efficiency, difficulty in complete mineralization, and the generation of toxic intermediates. Simultaneously, the filling medium is prone to deactivation due to passivation, blockage, or adsorption saturation, causing a rapid decline in remediation efficiency and insufficient long-term stability, making it difficult to meet the remediation needs of complex contaminated sites. Electro-Fenton (EF) technology, as an important branch of advanced oxidation technologies, generates highly oxidizing hydroxyl radicals through electrochemical catalysis, exhibiting excellent degradation capabilities for recalcitrant organic pollutants such as antibiotics. However, the practical application of this technology is limited by multiple conditions: it requires continuous external power supply, specific reactor construction, and an acidic reaction environment, and often necessitates the addition of soluble catalysts. These stringent requirements are severely incompatible with the neutral pH, low conductivity environment, and passive, low-maintenance operation needs faced by in-situ groundwater remediation, making it difficult to directly apply traditional electro-Fenton technology to in-situ groundwater remediation scenarios.

[0006] To combine the high-efficiency oxidation capacity of electro-Fenton technology with the in-situ remediation advantages of permeable reactive walls, and to overcome technical bottlenecks such as low groundwater conductivity, limited energy supply, and insufficient stability of the catalytic system, this invention aims to develop a novel integrated remediation technology that is energy-self-sufficient, highly efficient, stable, and environmentally friendly, achieving the complete removal of recalcitrant organic pollutants such as antibiotics from groundwater. The first aspect of this invention provides an electro-Fenton permeable reactive wall system, comprising:

[0007] The main body of the permeable reactive wall is a frame structure, and inlet and outlet are respectively provided on the two walls of the main body of the permeable reactive wall; An electro-Fenton reaction unit is disposed inside the permeable reactive wall body, comprising at least one pair of anodes and cathodes inserted into the wall body and connected to a power source; A solid electrolyte layer is disposed between the anode and the cathode; The photovoltaic energy unit is electrically connected to the electro-Fenton reaction unit.

[0008] The electro-Fenton osmosis reactive wall system of the present invention has at least the following beneficial effects: This invention achieves highly efficient in-situ remediation, breaking through the bottlenecks of traditional technologies. The permeable reactive barrier (PRB) in this invention, by setting inlet and outlet ports, ensures that contaminated groundwater flows directionally through the interior of the barrier. Combined with the built-in electro-Fenton reaction unit, it utilizes the electro-Fenton oxidation effect of oxygen evolution at the anode and the generation of hydroxyl radicals (·OH) at the cathode to non-selectively attack and thoroughly mineralize recalcitrant organic pollutants such as antibiotics. Compared to traditional permeable reactive barriers (PRBs) that rely on adsorption or chemical reduction, have low degradation efficiency, and are prone to producing toxic intermediate products, this design fundamentally improves the pollutant degradation efficiency and mineralization degree, while avoiding the decline in remediation effectiveness caused by passivation, blockage, and deactivation of the filling medium, significantly enhancing the long-term stability of the system.

[0009] The catalytic reaction system has been optimized, balancing environmental protection and long-term effectiveness. The synergistic effect of the anode and cathode in the electro-Fenton reaction unit, combined with the ion conduction function of the solid electrolyte layer, constructs a highly efficient heterogeneous catalytic system. Unlike traditional homogeneous electro-Fenton technology, it eliminates the need for additional soluble catalysts, thus avoiding secondary pollution from iron sludge and catalyst loss at the source. Furthermore, the active catalytic sites on the electrode surface are stably maintained, ensuring long-term catalytic performance and extending system lifespan, meeting the green, environmentally friendly, and low-maintenance requirements of in-situ groundwater remediation.

[0010] This design overcomes the limitation imposed by low conductivity, ensuring the system's efficient operation. A solid electrolyte layer filling the space between the anode and cathode provides a low-resistance channel for ion migration in saturated water conditions, effectively reducing the high internal resistance caused by the low conductivity of groundwater. This design significantly improves current efficiency and energy utilization, enabling the electro-Fenton reaction to operate stably and economically in groundwater environments with low to medium conductivity, overcoming a key obstacle in the in-situ application of electrochemical technology for groundwater remediation.

[0011] This system achieves energy self-sufficiency and 24 / 7 operation, expanding its application scenarios. The photovoltaic energy unit is electrically connected to the electro-Fenton reactor unit, converting solar energy into electricity to power the reactor unit. Combined with energy storage, it enables daytime power generation and storage, and nighttime / no-sunlight power supply. This design completely eliminates the system's dependence on industrial power grids, making it particularly suitable for remote areas and contaminated sites without grid coverage. It ensures continuous and uninterrupted remediation, providing reliable energy support for large-scale, long-term in-situ groundwater remediation, representing a truly green and sustainable remediation technology solution.

[0012] The system boasts high integration and significant engineering application potential. The permeable reactive barrier, electro-Fenton reaction unit, solid electrolyte layer, and photovoltaic energy unit form a compact and functionally synergistic integrated system. Anode oxygen evolution provides endogenous oxygen for the cathode reaction, the solid electrolyte ensures ion transport, and the photovoltaic unit provides stable power. All components work together to improve reactant utilization and overall repair efficiency. The system requires no external chemicals, has low maintenance needs, and controllable operating costs, possessing strong technological integration advantages and broad engineering application prospects.

[0013] This invention constructs a system that deeply integrates efficient electro-Fenton oxidation technology with the concept of in-situ remediation using permeable reactive barrier (PRB), solving the fundamental problems of low degradation efficiency of traditional PRB technology for recalcitrant organic pollutants such as antibiotics and the easy deactivation of the filling medium. Specifically, it utilizes the anode to achieve in-situ generation and catalytic decomposition of hydrogen peroxide, replacing the traditional homogeneous electro-Fenton model which requires an external soluble catalyst. This avoids secondary pollution and ensures the long-term effectiveness and stability of the catalytic effect, ultimately achieving efficient, thorough, and safe removal of organic pollutants such as antibiotics from groundwater. Furthermore, by introducing a solid electrolyte layer, the technical bottleneck of low system current efficiency and high energy consumption caused by the low conductivity of groundwater is effectively solved, ensuring the high efficiency and stability of the electrochemical process. Even further, the system achieves energy self-sufficiency and stable all-weather operation in the groundwater environment. By integrating a photovoltaic-energy storage unit, it eliminates dependence on grid power supply and overcomes the limitations of traditional electro-Fenton technology in remote sites.

[0014] The main body of the permeable reactive barrier is positioned along the path of the polluted groundwater plume.

[0015] According to some embodiments of the present invention, the frame structure of the permeable reactive wall is an underground wall constructed of impermeable material, with openings at the top and bottom of the front and rear walls to allow groundwater to flow in downwards and outwards. This main body provides structural support for the entire remediation system and ensures hydraulic flow.

[0016] According to some embodiments of the present invention, the inlet is located at the bottom of the permeable reactive barrier body, and the outlet is located at the top of the permeable reactive barrier body, so that the contaminated groundwater flowing through the permeable reactive barrier body forms a flow path of bottom inlet and top outlet.

[0017] According to some embodiments of the present invention, the permeable reactive wall body is disposed on the plume path of the contaminated groundwater, and the contaminated groundwater flows into the permeable reactive wall body from the inlet and flows out of the permeable reactive wall body from the outlet.

[0018] According to some embodiments of the present invention, the anode is a metal-carbon coated modified electrode, and the anode surface is provided with an anode coating of iron-cobalt bimetallic co-doped chitosan carbon aerogel.

[0019] By utilizing a bimetallic iron-cobalt heterogeneous catalytic electrode, in-situ generation and catalytic decomposition of hydrogen peroxide can be achieved, replacing the traditional homogeneous electro-Fenton method which requires the addition of an external soluble catalyst. This avoids secondary pollution and ensures the long-term effectiveness and stability of the catalytic effect, ultimately achieving efficient, thorough, and safe removal of organic pollutants such as antibiotics from groundwater.

[0020] According to some embodiments of the present invention, the molar ratio of iron to cobalt in the anodic coating is 1:(0.3~3).

[0021] According to some embodiments of the present invention, the molar ratio of iron to cobalt in the anodic coating is any one of the following values: 1:0.3, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, such as 1:1, or any range formed by both, such as 1:1 to 1:1.4.

[0022] According to some embodiments of the present invention, the molar ratio of iron to cobalt in the anodic coating is 1:1.

[0023] According to some embodiments of the present invention, the anode can be prepared by: dissolving chitosan in a dilute acetic acid solution to form a sol, adding iron salt and cobalt salt to the sol in a certain molar ratio, mixing thoroughly, and then freeze-drying to form an aerogel precursor. Finally, the precursor is carbonized at a temperature range of 600°C to 900°C for 1 to 3 hours under an inert atmosphere to obtain a carbon aerogel. This carbon aerogel is then ground and mixed with polyvinylidene fluoride (PVDF) in N-methyl-2-pyrrolidone (NMP) to form a slurry, which is then coated onto a commercial titanium mesh. Its function is to induce an oxygen evolution reaction under energized conditions, generating oxygen that diffuses to the cathode surface, continuously providing a substrate for the cathode reaction and forming an endogenous oxygen cycle within the system.

[0024] According to some embodiments of the present invention, the cathode is a metal-carbon coated electrode, and the anode surface is provided with a cathode coating of iron-cobalt bimetallic co-doped chitosan carbon aerogel.

[0025] According to some embodiments of the present invention, the molar ratio of iron to cobalt in the cathode coating is 1:(0.3~3).

[0026] According to some embodiments of the present invention, the molar ratio of iron to cobalt in the cathode coating is any value among 1:0.3, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, and 1:3, such as 1:1, or any range formed by both, such as 1:1 to 1:1.4.

[0027] According to some embodiments of the present invention, the molar ratio of iron to cobalt in the cathode coating is 3:1.

[0028] According to some embodiments of the present invention, the core function of the cathode is to efficiently reduce the oxygen generated at the anode to hydrogen peroxide (H2O2) with two electrons under the action of an electric field. At the same time, the iron and cobalt species loaded in the material can catalyze the decomposition of H2O2 in situ, generating highly active hydroxyl radicals (·OH) for the oxidative degradation of organic pollutants.

[0029] According to some embodiments of the present invention, the molar ratio of iron to cobalt in the cathode coating is greater than that in the anode coating. Because the cathode and anode have different functions—the cathode is used for in-situ catalytic generation of hydroxyl radicals, while the anode is used to release oxygen to supply the cathode reaction—the required iron-cobalt molar ratio during material preparation also differs.

[0030] The difference in the preparation details of the cathode and anode lies in the different molar ratio of iron and cobalt.

[0031] According to some embodiments of the present invention, the solid electrolyte layer comprises a hydrophilic polyurethane sponge.

[0032] According to some embodiments of the present invention, the photovoltaic energy unit includes a photovoltaic panel and an energy storage battery.

[0033] A second aspect of the present invention provides the application of the electro-Fenton permeation reactive wall system of the present invention in in-situ remediation of groundwater pollution.

[0034] The electro-Fenton permeable reactive wall system of this invention has significant and comprehensive beneficial effects in the in-situ remediation of groundwater pollution: It can rely on the in-situ layout of the permeable reactive wall body, combined with the strong oxidizing hydroxyl radicals generated by the electro-Fenton reaction unit, to efficiently and thoroughly mineralize recalcitrant organic pollutants such as antibiotics in groundwater, overcoming the problems of low degradation efficiency, easy generation of toxic intermediate products, and easy deactivation of the medium in traditional in-situ remediation technologies. Simultaneously, the solid electrolyte layer can effectively overcome the bottleneck of low groundwater conductivity, ensuring stable and efficient electrochemical reactions. The supporting application of photovoltaic energy units achieves energy self-sufficiency and continuous remediation around the clock, completely eliminating dependence on external power grids, making it particularly suitable for remote, pollution-free sites. Furthermore, this application does not require the addition of soluble catalysts, avoiding secondary pollution. The system has high overall integration, low maintenance requirements, and controllable operating costs. While achieving green and sustainable groundwater remediation, it provides a highly practical and widely adaptable technical solution for in-situ remediation of groundwater pollution in complex sites, possessing both environmental benefits and engineering application value. Attached Figure Description

[0035] Figure 1 This is a conceptual structure and physical diagram of an electro-Fenton osmotic reaction wall system.

[0036] Figure 2 This is a schematic diagram of the main structure of the permeable reactive wall.

[0037] Figure 3 This is a flowchart of the electrode preparation process in Example 1.

[0038] Figure 4 This is the electron paramagnetic resonance spectrum of the water sample in the cathode chamber.

[0039] Figure 5 This is a graph showing the test results of hydroxyl radicals generated by electrodes with different iron-cobalt molar ratios.

[0040] Figure 6 This is a graph showing the hydroxyl radical yield at the Fe3Co1-C cathode.

[0041] Figure 7 This is a linear sweep voltammetric curve of the oxygen evolution performance of electrodes with different iron-cobalt molar ratios.

[0042] Figure 8 This is a comparison chart showing the effect of introducing solid electrolytes on current response.

[0043] Figure 9 The graph shows the test results of the effect of introducing solid electrolyte on the degradation effect of the system.

[0044] Figure 10 This is an evaluation chart of the EF-PRB system's performance in degrading actual pharmaceutical wastewater.

[0045] Figure 11This is an assessment diagram of the energy consumption of the EF-PRB system. Detailed Implementation

[0046] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0047] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0049] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0050] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0051] Example 1 An electro-Fenton osmosis reactive barrier system is provided, including its conceptual structure and physical diagrams. Figure 1 As shown.

[0052] The main structure of the permeable reactive wall is as follows: Figure 2 As shown, the main body of the permeable reactive wall is a frame structure. Inlet and outlet (not shown) are respectively installed on the two walls of the main body, namely the PVC front baffle 1 and the PVC rear baffle 6. The electro-Fenton reaction unit is located inside the main body of the permeable reactive wall, including a pair of anodes 5 and cathodes 2 inserted into the wall and connected to a power source. A solid electrolyte layer 4 is located between the anodes 5 and cathodes 2. A photovoltaic energy unit (not shown) is electrically connected to the electro-Fenton reaction unit. A PVC partition 3 is installed between the cathode 2 and the solid electrolyte layer 4.

[0053] First, an iron-cobalt bimetallic co-doped chitosan-carbon aerogel electrode was prepared. This electrode is a heterogeneous catalytic electrode.

[0054] This embodiment details the preparation method of the heterogeneous catalytic electrode, the core component of this invention, and its preparation process is as follows: Figure 3 As shown. Specifically: (1) Preparation of precursor sol Weigh 2.0 g of chitosan powder and dissolve it in 100 mL of 2 wt.% acetic acid aqueous solution. Stir magnetically for 1 h until completely dissolved to form a transparent, uniform, pale yellow chitosan sol.

[0055] (2) Metal doping Cobalt nitrate hexahydrate and ferric nitrate nonahydrate were added sequentially to the chitosan sol, with the molar ratio of iron to cobalt controlled within the range of 0.3 to 3. Magnetic stirring was continued for 1 hour to ensure that the metal salts were fully dissolved and complexed with the chitosan molecular chains, resulting in an orange-red viscous FeCo-chitosan mixed sol.

[0056] (3) Freeze-drying The FeCo-chitosan mixed sol was poured into a polytetrafluoroethylene mold and frozen in an ultra-low temperature freezer at -40°C for 2 hours. Subsequently, the completely frozen sample was transferred to a freeze dryer and dried under a vacuum of less than 10 Pa for 48 hours. Ice crystals were removed to obtain the FeCo-chitosan aerogel precursor with a three-dimensional network structure.

[0057] (4) Pre-oxidation The aerogel precursor was placed in a tube furnace and slowly heated from 80°C to 200°C at a heating rate of 2°C / min under an oxygen atmosphere, and held at this temperature for 12 hours for pre-oxidation.

[0058] (5) High-temperature carbonization After pre-oxidation, the mixture is heated to 900°C at a rate of 5°C / min under a protective atmosphere of continuously purged high-purity nitrogen, and held at this temperature for 1 hour for carbonization. After the reaction is complete, it is naturally cooled to room temperature to obtain a black iron-cobalt bimetallic co-doped carbon aerogel mass.

[0059] (6) Electrode forming The carbonized bulk material was ground into powder. Then, the powder and the binder polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 8:1, and an appropriate amount of N-methyl-2-pyrrolidone solvent was added. The mixture was then ground to form a homogeneous slurry. A small electrode with a surface area of ​​1 cm × 1 cm was coated onto a titanium mesh current collector for the identification of hydroxyl radicals, yield testing, and oxygen evolution reaction testing. A large electrode was coated onto a pre-cleaned 575 cm × 300 cm × 0.1 cm titanium mesh current collector for the treatment of pharmaceutical wastewater containing antibiotics, with a coating loading of approximately 1 mg / cm². 2Finally, the coated electrode is dried at 60°C for 1 hour on a coating machine to obtain the heterogeneous catalytic electrode required by this invention.

[0060] In the case of a heterogeneous catalytic electrode, specifically, hydroxyl radicals are generated by the reaction of iron and hydrogen peroxide. If the iron is soluble (ferrous sulfate), then it is a homogeneous reaction. However, if the iron is insoluble (such as when it is modified on the electrode), then it involves solid iron catalyzing liquid hydrogen peroxide, which is a heterogeneous reaction.

[0061] Performance Test 1: Identification of Free Radical Types Generated at the Cathode This test example aims to directly identify and confirm, using electron paramagnetic resonance (EPR) technology, that in the EF-PRB system of this invention, ·OH is the dominant active species for degrading organic pollutants within the cathode-catalyzed reaction system. (Refer to...) Figure 4 As shown.

[0062] (1) Construction of the reaction tank The small electrode prepared in Example 1, with a carbon aerogel electrode (Fe3Co1-C) having an iron-cobalt molar ratio of 3:1, was used as the working cathode, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode. The experiment was conducted in a microreactor simulating an EF-PRB system. 100 mL of a 0.1 mol / L Na2SO4 solution was added to the reactor as the electrolyte, and the pH was adjusted to 3 using 1.0 mol / L H2SO4.

[0063] (2) Experimental procedure A constant potential of -0.8V vs. SCE is applied. After 5 minutes of electrolysis, 0.5 mL of water sample is rapidly aspirated from the region near the cathode using a pipette and immediately injected into a 10 μL quartz capillary containing 5,5-dimethyl-1-pyrrolline-N-oxide to form a longer-lived adduct.

[0064] (3) EPR test The sampled capillary was immediately placed on a Bruker EMXplus electron paramagnetic resonance spectrometer for testing. The test conditions were set as follows: central magnetic field 3510 G, scan width 100 G, microwave power 20 mW, modulation frequency 100 kHz, and modulation amplitude 1.0 G.

[0065] (4) Results and Analysis The obtained EPR spectrum showed a set of quartet characteristic peaks with an intensity ratio of 1:2:2:1. These characteristic peaks perfectly match the standard EPR spectrum of the DMPO-OH adduct. This demonstrates the successful generation of highly oxidizing ·OH in the iron-cobalt bimetallic cathode of this invention.

[0066] Performance Test 2: Efficiency of Hydroxyl Radical Generation by Electrodes with Different Iron-Cobalt Molar Ratios This test case aims to quantitatively determine the rate and accumulation of ·OH generated in an electro-Fenton system by using the Griess reagent colorimetric detection method for electrodes with different iron-cobalt molar ratios, thereby screening out the electrode composition with the best catalytic activity and providing core material support for the efficient operation of the entire system.

[0067] (1) Electrode preparation Carbon aerogel electrodes with iron to cobalt molar ratios of 3:1, 2:1, 1:1, 1:2, and 1:3 were prepared strictly according to the material preparation and electrode forming methods described in Example 1, and were denoted as Fe3Co1-CA, Fe2Co1-CA, Fe1Co1-CA, Fe1Co2-CA, and Fe1Co3-CA, respectively. All electrodes maintained consistent geometry, carbon loading, and coating processes. Cathode samples without metal modification were labeled C.

[0068] (2) Construction of experimental system See Performance Test 1, (1) Reaction Cell Setup. Add 2 mmol / L of 5-nitroimidazole to the electrolyte, apply a constant potential of -0.8V vs. SCE, and react for 90 min. Take samples for testing at the maximum absorption wavelength of 540 nm using a UV-Vis spectrophotometer.

[0069] (3) Principle of ·OH capture and determination Hydroxyl radicals react specifically with nitroimidazole compounds to release nitrite ions; subsequently, the nitrite ions react with Griess reagent to generate a red azo compound. The quantitative detection of hydroxyl radicals can be achieved by measuring its absorbance at 540 nm or by observing the color change with the naked eye.

[0070] (4) Results and Analysis The ·OH concentrations measured at different electrodes at various time points were plotted as ·OH production-time curves, such as... Figure 5 As shown.

[0071] The curves show that the ·OH yield of all Fe / Co bimetallic electrodes is significantly higher than that of pure carbon electrodes, demonstrating the superiority of bimetallic synergistic catalysis.

[0072] After 90 min of energization, the cumulative ·OH production of each electrode system, from highest to lowest, was as follows: Fe3Co1-C (161.44 μmol / L) > Fe2Co1-C (143.17 μmol / L) > Fe1Co1-C (121.96 μmol / L) > Fe1Co2-C (117.37 μmol / L) > Fe1Co3-C (105.57 μmol / L) > C (21.59 μmol / L). This indicates that, under the preparation conditions, the electrode catalytic efficiency for generating hydroxyl radicals is highest when the molar ratio of Fe to Co is 3:1. A higher iron content is more conducive to the formation of Fe-Nx active sites, which play a key role in the activation of H2O2 and the generation of ·OH. Appropriate cobalt doping optimizes the electronic structure of the carbon material, enhancing its conductivity and oxygen reduction performance; the synergistic effect of these two factors reaches its optimal balance at Fe:Co = 3:1. To further investigate the reaction kinetics of ·OH generation via Fe3Co1-C cathode catalysis, we conducted relevant experiments, and the results are as follows: Figure 6 As shown.

[0073] In the first 20 minutes of the reaction, the concentration of ·OH in the electrolyte showed a sharp upward trend, reaching 126.36 μmol / L in a short period of time; while in the following 70 minutes, the rate of increase in concentration slowed down significantly, gradually leveled off, and eventually reached a dynamic equilibrium.

[0074] Performance Test 3: Oxygen Evolution Performance of Electrodes with Different Iron-Cobalt Molar Ratios This test case aims to evaluate the oxygen evolution reaction activity of electrodes with different iron-cobalt molar ratios as anodes using linear sweep voltammetry (LSV) in order to determine the optimal anode material composition and thus ensure that the system can efficiently and stably provide the necessary oxygen for the cathode reaction.

[0075] (1) Electrode preparation Electrode preparation is shown in (1) of performance test 2.

[0076] (2) Construction of electrochemical three-electrode system Fe3Co1-C was used as the cathode, and Fe3Co1-CA, Fe2Co1-CA, Fe1Co1-CA, Fe1Co2-CA, Fe1Co3-CA and C were used as the anodes. A saturated calomel electrode was used as the reference. 100 mL of 0.1 mol / L Na2SO4 solution was added to the reactor as the electrolyte, and the pH was adjusted to 3 with 1.0 mol / L H2SO4.

[0077] (3) Testing process The working electrode was stabilized in the electrolyte at the open-circuit potential for 5 min, and then LSV tests were carried out: the scanning potential range was from the open-circuit potential of the material to 2.0 V vs. SCE, and the scanning rate was 10 mV / s. The catalytic activity of the oxygen evolution reaction (OER) is usually evaluated by the onset overpotential and the overpotential required to reach a reference current density (such as 10 mA / cm 2 ).

[0078] (4)Results and analysis It can be observed from Figure 7 that the potential at which the current of the Fe1Co3-CA electrode starts to increase significantly (i.e., the onset overpotential) is the lowest, about XX mV, indicating that the thermodynamic driving force required to initiate the OER reaction is the smallest and the oxygen evolution reaction is most likely to occur. When reaching the reference current density of 10 mA / cm 2 , the overpotentials required for each electrode from low to high are: Fe1Co1-C (η10 = 1.657 V) < Fe1Co3-C (η10 = 1.658 V) < Fe1Co2-C (η10 = 1.686 V) < Fe2Co1-C (η10 = 1.745 V) < Fe3Co1-C (η10 = 1.864 V) < C (η10 = 1.96 V). The Fe1Co1-C electrode requires the lowest overpotential, proving that it has the most excellent OER catalytic activity. The experimental results clearly show that the increase in Co content significantly improves the OER performance of the electrode. This is mainly because cobalt is considered to be an efficient OER active center. When Fe:Co is 1:1, the two form an atomically coordinated Fe-Co bimetallic active center, and this structure can optimally adjust its electronic state, so that the adsorption energy of the oxygen evolution reaction intermediate reaches an ideal balance point, making the reaction energy barrier the lowest. When the ratio of cobalt exceeds 1:1, the excess cobalt cannot form this optimal bi-atomic site anymore, but forms single-cobalt sites or cobalt clusters with lower intrinsic activity, so the catalytic performance does not increase significantly anymore, reaching a performance plateau. Therefore, the ratio of Fe and Co being 1:1 is the most preferred solution for constructing the high-performance anode of the electro-Fenton permeable reaction wall system of the present invention.

[0079] Performance test 4: Influence of the introduction of solid electrolyte on the degradation effect This test example aims to visually verify the key role of introducing polyurethane sponge as a solid electrolyte layer in improving the current response of the whole system and overcoming the bottleneck of groundwater conductivity through electrochemical tests.

[0080] (1)Experimental method A dual-electrode testing system simulating the EF-PRB core unit was constructed. The Fe1Co1-C electrode prepared in Example 1 was used as the anode, and the Fe3Co1-CA electrode as the cathode, with a fixed electrode spacing of 0.2 cm. The electrolyte was actual groundwater sample with a conductivity of 1057 μS / cm. In the experimental group, a hydrophilic polyurethane sponge fully saturated with ultrapure water was tightly filled between the anode and cathode as a solid electrolyte layer. In the control group, no polyurethane sponge was used; only groundwater was present between the electrodes. LSV testing was performed using an electrochemical workstation in the above dual-electrode system. The scanning voltage range was 0 V to 4.0 V, the scanning rate was 10 mV / s, and the current variation curve with the cell voltage (i.e., the voltage between the two electrodes) was recorded.

[0081] (2) Results and Analysis The obtained LSV curve is clearly shown (reference). Figure 8 As shown in the figure, under the same applied cell voltage, the current response of the experimental group (including solid electrolyte) was significantly higher than that of the control group. For example, at a cell voltage of 4.0V, the current density of the experimental group reached 35.11mA / cm². 2 The current density of the control group was only 12.01 mA / cm². 2 This result clearly demonstrates the core function of polyurethane sponge as a solid electrolyte layer. In a saturated water state, the sponge adsorbs and enriches ions in the solution, forming a stable, low-resistance ion conduction channel between the electrodes, significantly reducing the overall internal resistance of the system. In contrast, the control group relies solely on the low concentration of ions in the bulk solution for charge transport, resulting in extremely high internal resistance and a weak current response.

[0082] exist Figure 9 The image shows the change in degradation effect after introducing polyurethane foam. It can completely degrade enrofloxacin at an initial concentration of 20 mg / L within 60 minutes, while the degradation rate without solid electrolyte is only 35%. The introduction of the solid electrolyte layer effectively reduces the system's internal resistance and significantly increases the operating current, thereby ensuring the efficient and stable operation of the electro-Fenton permeation reactor in low-conductivity groundwater environments. This design is one of the key technical features that enabled the successful implementation of this invention.

[0083] Performance Test 5: Evaluation of the Degradation Performance of the EF-PRB System on Actual Pharmaceutical Wastewater in Groundwater This test case aims to quantitatively evaluate the actual degradation efficiency and stability of the EF-PRB system of this invention for complex and compound pollutants by treating real pharmaceutical wastewater, and to verify its potential for engineering applications.

[0084] (1) Experimental materials and methods The water source was actual medical wastewater from a hospital in Sichuan Province, China. The influent was transparent and colorless with a slight chemical odor. Its main pollutants, after pretreatment, were: Chemical Oxygen Demand (COD) 45.2 mg / L, pH 5.5, and conductivity 844 μS / cm. Seven typical antibiotics were identified using liquid chromatography-mass spectrometry (LC-MS / MS).

[0085] (2) Results and Discussion Experimental data Figure 10 The results show that after treatment by the EF-PRB system of this invention, through three treatment units, the pollutant removal efficiency increases progressively. The removal rates for sulfamethazine, penicillin G, decarboxylofloxacin, norfloxacin, sulfamethoxazole, levofloxacin, and chloramphenicol are 84.5%, 70.2%, 85.2%, 93.6%, 63.2%, 62.6%, and 68.5%, respectively. This embodiment, through the treatment of groundwater contaminated by complex pharmaceutical wastewater, fully verifies that the photovoltaic-driven EF-PRB system described in this invention has a highly efficient, deep, and stable removal capability for recalcitrant organic pollutants, especially antibiotics. This system not only significantly outperforms traditional remediation technologies but also successfully achieves energy self-sufficiency and continuous operation under simulated real-world conditions, providing strong experimental evidence and data support for its application in actual groundwater remediation projects.

[0086] Performance Test 6: Energy Consumption of the EF-PRB System This test case aims to quantitatively evaluate the operating energy consumption of the EF-PRB system and verify the feasibility and reliability of the system achieving energy self-sufficiency and all-weather operation by calculating the power generation capacity of the photovoltaic energy units. The results are as follows: Figure 11 As shown.

[0087] (1) Evaluation method Under stable operating conditions, the actual power consumption of the EF-PRB system, including three series-connected degradation units and the pump, was monitored. The average power consumption of the system at an operating voltage of 3.0V was measured to be 0.63kW / h. Furthermore, the installation area for this system is S=6m². 2 The polycrystalline silicon photovoltaic panel has a rated photoelectric conversion efficiency (η) of 18%. Solar irradiance under typical weather conditions was statistically analyzed and converted into photovoltaic energy output: rainy day (0.91 kW / h), cloudy day (1.81 kW / h), sunny day (2.54 kW / h), and sunny day (3.43 kW / h). Analysis shows that even under cloudy conditions with weak power generation, the energy generated by the photovoltaic system significantly exceeds the total daily energy consumption of the EF-PRB system, resulting in a substantial energy surplus. Under sunny conditions, the energy surplus is even greater. This surplus will be stored in energy storage batteries for use at night or during periods without sunlight to power the system. These calculations fully demonstrate the effectiveness of the 6m² photovoltaic system. 2 The energy provided by the photovoltaic system with a conversion efficiency of 18% is sufficient to cover and meet the all-weather operation requirements of the EF-PRB system under different weather conditions.

[0088] This embodiment, through energy consumption measurement and power generation calculation, confirms that the photovoltaic-driven EF-PRB system described in this invention can achieve energy self-sufficiency. The system operates with low energy consumption and can be fully powered by a moderately sized photovoltaic-energy storage system, completely eliminating dependence on industrial power grids. This characteristic makes this invention particularly suitable for groundwater remediation in remote areas and sites without power grid coverage, representing a truly green, low-carbon, and sustainable environmental governance technology.

[0089] Compared with the prior art, the system and its application method provided by the present invention have the following significant advantages: First, this invention achieves a deep integration of efficient oxidation and in-situ remediation, overcoming the technical bottlenecks of traditional PRB (Potentially Regenerated Bioreactor). It successfully integrates EF (Enhanced Fluid Extraction) technology into the physical framework of PRB, generating highly oxidizing ·OH in situ via electrochemical means. This ·OH can non-selectively and efficiently attack and completely mineralize recalcitrant organic compounds such as antibiotics, fundamentally overcoming the problems of low degradation efficiency and the generation of toxic intermediates caused by traditional PRBs relying on adsorption or reduction pathways. The "bottom-in, top-out" water flow design of the reaction wall optimizes the hydraulic residence time, ensuring sufficient contact and reaction between pollutants and active free radicals.

[0090] Secondly, a bifunctional heterogeneous catalytic electrode was employed, achieving long-term stability and environmental friendliness in the catalytic process. This invention uses iron-cobalt bimetallic co-doped chitosan carbon aerogel to simultaneously modify both the anode and cathode. The cathode plays a core role, not only efficiently reducing oxygen generated at the anode to H2O2, but also utilizing its own supported iron and cobalt active sites to catalyze the in-situ decomposition of H2O2 to produce ·OH. This design eliminates the need for continuous addition of soluble ferrous salts in traditional homogeneous electro-Fenton technology, fundamentally avoiding secondary pollution from iron sludge and catalyst loss. The heterogeneous catalyst is stably fixed on the electrode surface, ensuring long-term stability of catalytic activity and significantly extending the system's lifespan.

[0091] Third, the introduction of a solid electrolyte layer effectively overcomes the inherent challenge of low conductivity in groundwater. By filling the space between the electrodes with hydrophilic polyurethane sponge as a solid electrolyte layer, the system provides a stable, low-resistance channel for ion migration in a saturated water state. This design significantly reduces the system's internal resistance, substantially improves current efficiency and energy utilization, and enables the efficient electro-Fenton process to operate stably and economically in groundwater with medium to low conductivity, thus solving a core obstacle limiting the in-situ application of electrochemical technology.

[0092] Fourth, a photovoltaic-energy storage system was constructed, achieving complete energy self-sufficiency and 24 / 7 operation during the remediation process. By integrating photovoltaic panels and energy storage batteries, this system completely eliminates dependence on industrial power grids, making it particularly suitable for remote areas or contaminated sites without electricity. The system enables an energy cycle of "generating electricity during the day and using it at night," ensuring continuous and uninterrupted remediation. It provides a reliable energy solution for large-scale, long-term in-situ groundwater remediation, representing a truly green and sustainable remediation technology.

[0093] Fifth, the system boasts high integration and significant synergistic effects, demonstrating excellent engineering application prospects. This invention highly integrates the energy unit, catalytic electrode, electrolyte layer, and reaction wall structure, forming a compact and fully functional integrated repair system. An efficient internal oxygen cycle is established between the anodic oxygen evolution and the cathodic oxygen reduction and Fenton reaction, improving reactant utilization. The entire system requires no external chemicals, has low maintenance needs, and controllable operating costs, showcasing strong technological integration advantages and broad engineering application potential.

[0094] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An electro-Fenton osmosis reactive wall system, characterized in that, include: The main body of the permeable reactive wall is a frame structure, and inlet and outlet are respectively provided on the two walls of the main body of the permeable reactive wall; An electro-Fenton reaction unit is disposed inside the permeable reactive wall body, comprising at least one pair of anodes and cathodes inserted into the wall body and connected to a power source; A solid electrolyte layer is disposed between the anode and the cathode; The photovoltaic energy unit is electrically connected to the electro-Fenton reaction unit.

2. The electro-Fenton osmosis reactive wall system according to claim 1, characterized in that, The inlet is located at the bottom of the permeable reactive barrier body, and the outlet is located at the top of the permeable reactive barrier body. The contaminated groundwater flowing through the permeable reactive barrier body forms a flow path from bottom to top.

3. The electro-Fenton osmosis reactive wall system according to claim 1, characterized in that, The permeable reactive barrier is positioned on the plume path of the contaminated groundwater. The contaminated groundwater flows into the permeable reactive barrier from the inlet and flows out from the outlet.

4. The electro-Fenton osmosis reactive wall system according to claim 1, characterized in that, The anode is a metal-carbon coated electrode, and the anode surface is provided with an anode coating of iron-cobalt bimetallic co-doped chitosan carbon aerogel.

5. The electro-Fenton osmosis reactive wall system according to claim 4, characterized in that, The molar ratio of iron to cobalt in the anodic coating is 1:(0.3~3).

6. The electro-Fenton osmosis reactive wall system according to claim 1, characterized in that, The cathode is a metal-carbon coated electrode, and the cathode surface is coated with an iron-cobalt bimetallic co-doped chitosan carbon aerogel cathode coating.

7. The electro-Fenton osmosis reactive wall system according to claim 6, characterized in that, The molar ratio of iron to cobalt in the cathode coating is 1:(0.3~3).

8. The electro-Fenton osmosis reactive wall system according to claim 6, characterized in that, The solid electrolyte layer comprises a hydrophilic polyurethane sponge.

9. The electro-Fenton osmosis reactive wall system according to claim 1, characterized in that, The photovoltaic energy unit includes photovoltaic panels and energy storage batteries.

10. The application of the electro-Fenton infiltration reactive barrier system as described in any one of claims 1 to 9 in in-situ remediation of groundwater contamination.

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