Iron-molybdenum double-site synergistically enhanced electro-Fenton system and method for synchronously removing heavy metals and organic pollutants in water by iron-molybdenum double-site synergistically enhanced electro-Fenton system

Abstract

The invention discloses an iron-molybdenum double-site synergistically enhanced electro-Fenton system and a method for synchronously removing heavy metal and organic pollutants in water through the iron-molybdenum double-site synergistically enhanced electro-Fenton system. The electro-Fenton system comprises a metal anode and a cathode, and the cathode comprises a graphite oxide felt loaded with iron-doped molybdenum disulfide microspheres; the iron-doped molybdenum disulfide microspheres comprise a nanosheet structure formed by iron, molybdenum and sulfur, and the content of Fe in the iron-doped molybdenum disulfide microspheres is 0.5-4 wt%. According to the preparation method, an electro-catalysis system is constructed by three-dimensional iron-doped molybdenum disulfide graded microspheres (Fe-MoS2HS) and graphite oxide felt (GF), H2O2 is synergistically activated by utilizing Fe-Mo double sites, a composite oxide species of. OH and < 1 > O2 is formed, valence state circulation of Fe < 3 + > / Fe < 2 + > and Mo < 6 + > / Mo < 4 + > is combined, the bottlenecks of catalytic efficiency and stability in the prior art are broken through, and the preparation method has the advantages that the preparation method is simple and easy to implement, and the application prospect is wide. The efficient and synchronous removal of heavy metals and organic matters is realized (the removal rate is greater than or equal to 95%), the energy consumption is reduced by more than 40% compared with that of the traditional electro-Fenton, and the method has remarkable technical advancement and practicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment and relates to an iron-molybdenum dual-site synergistically enhanced electro-Fenton system and a method for simultaneously removing heavy metals and organic pollutants in water. Background Art

[0002] With the acceleration of industrialization, the number of refractory substances generated in industrial production is increasing. Traditional pollutant treatment technologies are ineffective in treating these substances. Advanced oxidation processes (ADOs) have emerged due to their superior degradation capabilities. Electro-Fenton technology, a type of ADO, has attracted widespread attention from researchers due to its strong oxidation capacity and minimal secondary pollution.

[0003] Electro-Fenton technology is an electrochemical advanced oxidation process based on the in-situ generation of hydroxyl radicals (·OH). In this process, the reagent H2O2 required to generate ·OH is generated by a two-electron reduction reaction of O2 on the cathode material, while traditional Fenton technology requires the external addition of H2O2 and Fe 2+ Electro-Fenton technology offers significant advantages over conventional electro-Fenton systems, which often require salt and face difficulties in storing and transporting H2O2. However, current electro-Fenton systems generally suffer from low H2O2 yields, severely limiting their large-scale industrial application. Because H2O2 production relies on cathode materials, developing cathode materials with excellent two-electron oxygen reduction performance for H2O2 production is crucial for this research.

[0004] At the same time, the issue of heavy metal pollution in water cannot be ignored. Heavy metals, as major wastewater pollutants, are non-biodegradable and accumulate in ecosystems. Their persistence, toxicity, and cumulative effects in the human body have prompted the search for new and more efficient water treatment technologies to reduce heavy metal concentrations in water. Traditional treatment technologies are increasingly unable to meet increasingly stringent standards for heavy metal content in drinking water and wastewater.

[0005] Some existing treatment methods have numerous shortcomings in the simultaneous removal of heavy metals and organic pollutants from water, facing challenges such as low catalytic efficiency, high energy consumption, and insufficient synergy. While existing patented technologies can achieve certain treatment results, they suffer from deficiencies in catalyst structure design, reaction mechanism optimization, and practical stability. Catalyst activity and stability need to be further improved. For example, Yang Bo et al. (CN115417530A) employed a Fenton-like system combining zero-valent iron with hydrogen peroxide. While this system can simultaneously remove pollutants, the zero-valent iron is susceptible to passivation, resulting in low H2O2 decomposition efficiency. Furthermore, the system requires continuous pH adjustment between 2.0 and 6.0, increasing process complexity. The synergistic mechanism is limited, and the mineralization rate needs to be further improved. Li Yanhong et al. (CN119660971A) employed iron-carbon materials in conjunction with Shewanella to remove organophosphorus and heavy metals. This method, which relies on the physical synergy of microbial metabolism and material adsorption, has limited mineralization for complex pollutants (such as perfluorinated compounds), resulting in a TOC removal rate of only 67% to 93%. The electro-flocculation coupled PMS system proposed by Dong Wenjie et al. (CN117682632A) produces sulfate radicals by electroactivating PMS, but the PMS dosage needs to be 0.1-2.0 mol / L, the reagent cost is high, and the iron flocs easily clog the electrodes, affecting the continuous reaction.

[0006] In summary, the existing technology lacks an efficient dual-site synergistic mechanism in catalyst design, the reaction system has high energy consumption and reagent costs, and is not adaptable to complex wastewater matrices. Summary of the Invention

[0007] The present invention aims to provide an iron-molybdenum dual-site synergistically enhanced electro-Fenton system and a method for simultaneously removing heavy metals and organic pollutants from water, so as to solve the problems of low efficiency, high cost, and poor stability in the existing technology for treating wastewater containing heavy metals and organic pollutants. Specifically, the present invention realizes an efficient electro-Fenton reaction by constructing a special catalyst structure and electrode system. In order to achieve the above-mentioned invention objectives, the technical solution adopted by the present invention is:

[0008] One aspect of the present invention relates to an electro-Fenton system, comprising a metal anode and a cathode, wherein the cathode comprises graphite oxide felt loaded with iron-doped molybdenum disulfide microspheres, wherein the iron-doped molybdenum disulfide microspheres comprise nanosheet structures formed of iron, molybdenum, and sulfur, and wherein the Fe content in the iron-doped molybdenum disulfide microspheres is 0.5-4 wt%, preferably 1-2 wt%. The present invention constructs an electrocatalytic system using three-dimensional iron-doped molybdenum disulfide hierarchical microspheres (Fe-MoS2HS) and graphite oxide felt (GF), utilizing the Fe-Mo dual-site synergistic activation of H2O2 to form ·OH and 1 O2 composite oxide species, combined with Fe 3 + / Fe 2+ and Mo 6+ / Mo 4+ Valence cycle breaks through the bottleneck of catalytic efficiency and stability in existing technologies, achieves efficient simultaneous removal of heavy metals and organic matter (removal rate ≥ 95%), and reduces energy consumption by more than 40% compared with traditional electro-Fenton, with significant technological advancement and practicality. In terms of reaction mechanism, the Fe-Mo dual sites in Fe-MoS2HS work synergistically to effectively activate H2O2 and generate ·OH and 1O2 with strong oxidizing properties. At the same time, combined with Fe 3+ / Fe 2+ and Mo 6+ / Mo 4+ Valence state circulation accelerates electron transfer and realizes efficient redox of heavy metals (such as Cr(VI)) and organic pollutants (such as BPA, perfluorinated compounds, antibiotics, phenols or endocrine disruptors, etc.) in water, thereby achieving the purpose of simultaneous removal.

[0009] In a preferred embodiment of the present invention, the metal anode is a platinum electrode.

[0010] In a preferred embodiment of the present invention, the iron-doped molybdenum disulfide microspheres are formed by the following steps: dissolving ammonium molybdate and thiourea in water, adding an Fe(NO3)3 solution, conducting a hydrothermal reaction at 200-240°C, separating the product by centrifugation, and drying to obtain the iron-doped molybdenum disulfide microspheres. The key to this invention lies in the use of three-dimensional iron-doped hierarchical molybdenum disulfide microspheres (Fe-MoS2HS) as a catalyst. These microspheres are synthesized via a hydrothermal method, with Fe doped at a mass ratio of 0.5%-4%, forming a 1T / 2H mixed phase with a specific surface area of ​​12.53 m2 / g. This unique structural design provides the catalyst with abundant active sites, facilitating subsequent catalytic reactions. The Fe-MoS2HS is loaded onto graphite oxide felt (GF) pretreated by electrochemical oxidation, forming the cathode, which forms a two-electrode system with a platinum anode. Pretreatment of the GF increases its surface oxygen-containing functional groups, improving its hydrophilicity and electrocatalytic activity, and boosting the efficiency of H2O2 electrogeneration.

[0011] In a preferred embodiment of the present invention, the electro-Fenton body system also includes a single-chamber electrolytic cell, a peristaltic pump and an air pump, the peristaltic pump is used to deliver sewage into the single-chamber electrolytic cell, the air pump is used to deliver air to the air pump, and the metal anode and cathode are located in the single-chamber electrolytic cell.

[0012] Another aspect of the present invention relates to a method for simultaneously removing heavy metals and organic pollutants from water, the method comprising treating water containing heavy metals and organic pollutants through the above-mentioned electro-Fenton system.

[0013] In a preferred embodiment of the present invention, the heavy metal includes hexavalent chromium.

[0014] In a preferred embodiment of the present invention, the organic pollutants include at least one of bisphenols, perfluorinated compounds, antibiotics, halogenated phenols and endocrine disruptors, or a combination of more than one of the group consisting of bisphenols, perfluorinated compounds, antibiotics, halogenated phenols and endocrine disruptors.

[0015] In a preferred embodiment of the present invention, the water containing heavy metals and organic pollutants further contains chloride ions.

[0016] The beneficial effects of the present invention are:

[0017] 1. Highly Efficient Synergy: The dual-site effect significantly increases the reaction rate. Compared to traditional systems, the reaction rate of this invention is increased by 9.75-18.96 times, and the mineralization rate is increased by 10.31 times. This is due to the synergistic effect of the Fe-Mo dual site, which can more efficiently activate H2O2, generate more strong oxidizing free radicals, and accelerate the redox reaction of pollutants.

[0018] 2. Universal Stability: The electro-Fenton system of this invention is applicable to a variety of wastewater matrices, demonstrating excellent treatment results for industrial wastewater, domestic sewage, and other complex waters. Low Fe / Mo dissolution during continuous flow operation demonstrates the catalyst's high stability and reusability, enabling it to be reused more than five times, reducing operating costs and improving practicality.

[0019] 3. Cost Advantage: By optimizing the catalyst structure and reaction system, we reduce reagent usage and energy consumption while ensuring efficient treatment results. Compared with some existing technologies, this invention reduces energy consumption by approximately 40% and reagent costs by over 50% while achieving high pollutant removal rates (≥95%).

[0020] 4. Versatility: It can simultaneously remove heavy metals and organic pollutants in water, solving multiple pollution problems in one treatment. It avoids the cumbersome process of using different treatment processes for different pollutants in traditional methods, improves treatment efficiency, and saves treatment time and equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of electrocatalytic device and reaction mechanism

[0022] Figure 2 (a) Schematic diagram of the synthesis of three-dimensional Fe-MoS2 HS with Fe-doped MoS2 hierarchical microspheres. (b) SEM image and (cd) HR-TEM images of Fe-MoS2 HS. (eh) Energy dispersive spectra of Fe-MoS2 HS.

[0023] Figure 3 Schematic diagram of the continuous flow electrocatalytic system

[0024] Figure 4Effects of (a) Fe doping amount and (b) catalyst dosage on the electrocatalytic degradation activity of BPA

[0025] Figure 5 Effects of (a) current density and (b) pH value on the electrocatalytic degradation of BPA.

[0026] Figure 6 (a) Comparison of the performance of different electrocatalytic systems for BPA degradation, (b) corresponding fitted reaction kinetic rate diagram. (c) Evaluation of electrocatalytic BPA degradation activity in actual water. (d) Stability test of more than 5 cycles of operation in the Fe-MoS2 HS / GF system. [Conditions: C BPA0 =10mg / L, pH=3, current density=5mA / cm 2 ].

[0027] Figure 7 : Simultaneous removal of (a) BPA and (b) Cr(VI) using different electrocatalytic systems. (c) Removal efficiency of BPA against TOC in different systems. (d) Kinetics of simultaneous electrocatalytic removal of Cr(VI) and different types of organic pollutants (PFAS, EDCs, antibiotics, phenols) using the Fe-MoS2 HS / GF system. [Condition: C pollutant = C Cr0 =10mg / L, pH=3, current density=5mA / cm 2 ].

[0028] Figure 8 :(a) Reusability of the Fe-MoS2 HS / GF system for simultaneous electrocatalytic removal of Cr(VI) and BPA, and (b) the corresponding BPA TOC removal efficiency in 5 operation cycles. (c) Experimental performance of the Fe-MoS2 HS / GF system for continuous electrocatalytic removal of wastewater treatment plant effluent at different flow rates, and (d) the corresponding Vibrio fischeri bioluminescence inhibition rate and TOC removal efficiency. [Conditions: C BPA0 =C Cr0 =10mg / L, pH=3, current density=5mA / cm 2 ].

[0029] Figure 9 : Long-term electrocatalytic activity of Fe-MoS2HS / GF system for simultaneous removal of BPA and Cr(VI). DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1:

[0032] 1. Catalyst Preparation

[0033] 0.1mmol ammonium molybdate and 2.5mmol thiourea were dissolved in 30mL water, 2% Fe(NO3)3 solution was added, and the reaction was carried out at 220℃ for 18h. After the reaction, the product was separated by centrifugation and dried to obtain Fe-MoS2HS (three-dimensional iron-doped molybdenum disulfide hierarchical microsphere catalyst, where HS represents hierarchical microspheres). The synthesis diagram and SEM, HR-TEM, and EDS characterization results are shown in Figure 2. Figure 2 shown.

[0034] The structure and composition of Fe-MoS2HS and graphite felt (GF) were systematically analyzed by various characterization methods (SEM, HR-TEM, EDS, XRD, Raman, XPS). SEM and HR-TEM showed that Fe-MoS2HS was a porous hierarchical microsphere structure (formed by self-assembly of nanosheets), which had a larger specific surface area and looser stacking than MoS2HS without Fe doping, which was conducive to providing more active sites and mass transfer space. EDS confirmed that Mo, S, and Fe elements were uniformly distributed on the surface of the material, directly proving that Fe was successfully doped. XRD and Raman spectra showed that Fe doping increased the crystallinity of MoS2 and formed a 1T / 2H mixed phase (1T phase has higher conductivity and catalytic activity), which provided a structural basis for subsequent electron transport and catalytic reactions. XPS analysis showed that there was Mo in the material. 4+ / Mo 6+ The characteristic valence state of Fe and Fe, and the formation of chemical bonds between Fe and S indicate that Fe is not simply physically mixed, but is chemically incorporated into the MoS2 lattice, laying the foundation for the synergistic effect of the dual active sites (Fe-Mo).

[0035] These characterization results collectively demonstrate the successful preparation of Fe-MoS2HS, and its structural and chemical properties are conducive to enhancing the subsequent electrocatalytic performance, providing a material basis for the simultaneous removal of Cr(VI) and organic pollutants.

[0036] 2. Electrode construction:

[0037] 2.1 Electrochemical oxidation pretreatment of GF electrode:

[0038] Graphite felt (GF) was immersed in a 1M sulfuric acid (H2SO4) solution and anodized at a constant current of 200 mA for 10 minutes. The goal was to modify the GF surface through electrochemical oxidation, increase its surface oxygen-containing functional groups (such as hydroxyl and carboxyl groups), enhance the GF's hydrophilicity and electrocatalytic activity, and promote the subsequent electrogeneration efficiency of H2O2.

[0039] 2.2 Preparation of Fe-MoS2HS ink:

[0040] Weigh 4 mg of Fe-MoS2HS powder as the catalyst, add 0.2 mL of ethanol as the dispersion medium, 0.05 mL of ultrapure water to adjust the viscosity, and 3 μL of Nafion solution (5 wt%) as the binder. After mixing these components, use sonication or stirring to create a uniform suspension, the Fe-MoS2HS ink.

[0041] 2.3 Preparation and drying of electrodes:

[0042] The prepared Fe-MoS2HS ink is drop-coated onto the pretreated GF surface. The effective area can be adjusted as needed, typically 1 x 1 cm2. After drop-coating, the solution is dried at 60°C to evaporate the solvent and ensure the catalyst adheres firmly to the GF, forming a stable electrocatalytic electrode (the Fe-MoS2HS is supported on graphite oxide felt (GF) to form the cathode).

[0043] 3. Electrocatalytic simultaneous removal of heavy metals and organic pollutants in water:

[0044] 3.1 Sequencing Batch Electrocatalysis:

[0045] In a 50mL single-chamber electrolytic cell, 0.05M Na2SO4 was used as the electrolyte. Mixed wastewater containing heavy metals and organic pollutants was added. The experimental simulated wastewater concentration was 10mg / L of bisphenol A (BPA) and hexavalent chromium Cr(VI). Electrode system: Fe-MoS2HS loaded on graphite oxide felt (GF) formed the cathode (Fe-MoS2HS / GF cathode), and formed a two-electrode system with a platinum anode. At a current density of 5mA / cm 2 The reaction was carried out under the following conditions and the reaction time was 60 minutes, achieving a 100% removal rate for BPA and Cr(VI). In actual applications, the reaction conditions, such as electrolyte concentration, initial pollutant concentration, current density, and reaction time, can be appropriately adjusted according to the wastewater quality and treatment requirements to achieve the best treatment effect.

[0046] 3.2 Flow Electrocatalysis:

[0047] Schematic diagram of the continuous flow electrocatalytic experiment performed by closed-loop operation at room temperature ( Figure 3 The experimental setup includes a peristaltic pump, an air pump, and an S-shaped reflux tube for adjusting the flow rate. Operating conditions: The effective area of ​​the GF cathode is 8 × 8 cm 2 , current density = 5mA / cm 2 , catalyst dosage 334 mg (scaled up), C BPA0 =C Cr0=10 mg / L, pH = 3, using 2 L of wastewater treatment plant (WWTP) effluent as the background water matrix. Samples were collected regularly between electrolysis intervals for subsequent analysis. The entire continuous flow electrocatalytic system is simple and efficient, allowing for post-reaction catalyst recovery, thereby improving catalyst reusability.

[0048] Optimization of experimental conditions for electrocatalytic degradation of BPA by Fe-MoS2HS / GF

[0049] Through a series of parallel experiments ( Figure 4 and Figure 5 ), we optimized the experimental conditions for the electrocatalytic degradation of BPA by Fe-MoS2HS / GF as follows: initial pH 3, Fe-MoS2HS catalyst dosage 8 mg, Fe doping amount 2 wt%, applied current density 5 mA / cm 2 .

[0050] Firstly, the effect of different Fe doping concentrations on the electrocatalytic degradation of BPA in the Fe-MoS2HS / GF system was studied. Figure 4 (a) shows that at an initial electrolyte pH of 3, the BPA degradation efficiency is only 85.8% when the Fe doping concentration is 0.5%. This phenomenon suggests that the lower doping concentration may lead to insufficient formation of active sites. However, the high Fe doping concentration (4%) may destroy the intrinsic structure of MoS2, thereby reducing the material's ability to catalyze the activation of H2O2. Figure 4 (b) shows that the optimal dosage of Fe-MoS2HS co-catalyst is 8 mg. Insufficient dosage may lead to a lack of catalytic sites in the system, thus affecting the reaction kinetics; while excessive dosage may affect the conductivity of the electrolyte, thereby hindering the electron transfer process.

[0051] Current density and electrolyte pH are key operating parameters that significantly affect the performance of the electrocatalytic system. We investigated the effect of different current densities on the electrocatalytic degradation of BPA. Figure 5 As shown in (a), the current density was increased from 1 mA / cm 2 Increased to 5mA / cm 2 When the cathode current density is 5 mA / cm 2 However, when the current density increased to 7 mA / cm 2 When the degradation efficiency dropped from 100% to 85.5%, it was mainly attributed to the hydrogen evolution side reaction at the GF cathode, which reduced the overall current utilization efficiency. Figure 5(b) shows that the electrocatalytic degradation efficiency of BPA by the Fe-MoS2HS / GF system is always over 90% in the pH range of 1-9, highlighting the wide pH applicability of the system. Therefore, the optimal current density is determined to be 5 mA / cm 2 , the ideal initial pH value of the electrolyte is 3.

[0052] 3.4 Performance of Fe-MoS2HS / GF in electrocatalytic degradation of BPA

[0053] like Figure 6 (a) and Figure 6 As shown in (b), when GF was used as the cathode, the catalytic degradation efficiency of BPA was significantly lower (<20%) after 1 hour of reaction, indicating that the in situ generated H2O2 was not sufficient to effectively degrade BPA. In contrast, the Fe-MoS2HS / GF system achieved nearly 100% BPA degradation efficiency after 40 minutes, with a reaction kinetic rate constant (8.30×10 -2 min -1 ) is the MoS2HS / GF system (3.40×10 -2 min -1 This proves that the Fe-MoS2HS powder co-catalyst has excellent catalytic activity and can significantly improve the efficiency of electrocatalytic degradation of BPA.

[0054] We further explored the potential applications of the Fe-MoS2HS / GF electrocatalytic system in four real water bodies. Figure 6 As shown in (c), when sewage treatment plant effluent (WWTP) was used as the background water matrix, it had no significant effect on the degradation of BPA; although groundwater inhibited the reaction kinetics of BPA, its removal efficiency could still reach 97.6%; when tap water and seawater were used as the background water matrix, both showed a promoting effect, among which seawater had a more obvious promoting effect on the electrocatalytic degradation of BPA. This may be related to the presence of free chlorine in the two water bodies. Free chlorine can generate active species (such as Cl or HClO) through electrocatalysis, thereby accelerating the degradation process of BPA. This shows that the Fe-MoS2HS / GF electrocatalytic system performs well in treating complex actual water bodies. In addition, the cyclic stability test of the Fe-MoS2HS / GF electrocatalytic system showed that the degradation and removal efficiency of BPA of the system remained above 95% during five repeated uses, and the kinetic rate was relatively stable, indicating that it has good stability and application potential in wastewater remediation, such as Figure 6 However, heavy metals often coexist with organic pollutants in real wastewater. Given the complexity of this system, it is urgent to explore the redox properties of the Fe-Mo dual site, which may provide a new approach to solving problems related to multi-component wastewater treatment.

[0055] 3.5 Simultaneous electrocatalytic removal of Cr(VI) and EOPs by Fe-MoS2HS / GF

[0056] Figure 7 ab shows that the Fe-MoS2HS / GF system exhibits a rapid and complete removal effect on BPA and Cr(VI). The kinetic reaction rate constant (k BPA and k Cr(VI) ) are 18.96 and 9.75 min higher than those of the MoS2 / GF system, respectively. -1 . It is worth noting that the MoS2 / GF system exhibits an antagonistic effect in treating these two pollutants. This phenomenon highlights the excellent catalytic redox activity of the Fe-MoS2HS / GF system, which can generate abundant active species and sites, thereby efficiently oxidizing BPA and reducing Cr(VI). In terms of mineralization efficiency, the Fe-MoS2HS / GF system significantly improves the mineralization efficiency of BPA, which is 10.31 times higher than that of the MoS2 / GF system ( Figure 7 c) In the single pollutant degradation scenario, the addition of Fe-MoS2HS reduced the oxidation kinetics of BPA from 3.35×10 -2 min -1 Increased to 8.29×10 -2 min -1 (2.47 times), the reduction kinetic rate of Cr(VI) was increased from 0.88×10 -2 min -1 Increased to 2.38×10 -2 min -1 (2.70-fold). Furthermore, the mineralization efficiency of BPA increased by 2.44-fold. This highlights its effectiveness in simultaneous electrocatalysis and confirms the crucial dual role of the Fe-MoS2HS co-catalyst's bimetallic active sites in the electro-Fenton system. These roles, leveraging the excellent redox catalytic capabilities of its surface-exposed active sites, enable the efficient, synergistic removal of Cr(VI) and BPA.

[0057] In order to evaluate the universal application of the Fe-MoS2HS / GF system for the synergistic electrocatalytic degradation of heavy metals and various organic pollutants, we selected several representative organic pollutants: perfluorinated compounds, antibiotics, halogenated phenols and endocrine disruptors ( Figure 7 Overall, the Fe-MoS2HS / GF system demonstrated effectiveness in treating Cr(VI) and various organic pollutants (such as antibiotics, halogenated phenols, and endocrine disruptors), demonstrating its versatility. Furthermore, it exhibited moderate defluorination effects on persistent perfluorinated compounds. These advantages suggest its broad application prospects in the coordinated treatment of heavy metal-organic wastewater.

[0058] 3.6 Environmental Applications of Fe-MoS2HS / GF

[0059] In order to further explore the rapid and synchronous removal capability of the Fe-MoS2HS / GF system for electrocatalytic activity, we studied its stability in repeated use tests and non-steady-state continuous flow operating systems. Figure 8 ab show that after five cycles (1 hour each cycle), the removal efficiency of BPA and Cr(VI) of the Fe-MoS2HS / GF system always remained at a high level (>95%), and the total organic carbon (TOC) removal efficiency exceeded 50%. Figure 3 The flow chart of the Fe-MoS2HS / GF system for non-steady-state continuous flow electrocatalytic wastewater treatment in practical applications is presented. Considering that the electrolyte flow rate affects the electrochemical reaction kinetics, we conducted experiments at different flow rates (1, 3, and 5 mL min -1 ) to evaluate the performance of the Fe-MoS2HS / GF system, we collected secondary effluent from the sewage treatment plant and added BPA and Cr(VI) as indicators of organic matter and heavy metal removal, and evaluated its long-term stability through 400 minutes of continuous operation. Figure 6 As shown in c, during the first 100 min of continuous operation, the flow rate was reduced from 1 mL min -1 Increase to 3 mL min -1 When the flow rate was further increased from 3 mL min -1 Increase to 5 mL min -1 When the flow rate was high, the removal efficiency of both pollutants decreased. Although the fast flow rate enhanced the mass transfer process of the reaction, the insufficient reaction time resulted in incomplete contact reaction, which in turn reduced the kinetic rate. This highlights the importance of effluent flow rate in non-steady-state continuous flow operating systems. In addition, the system still maintained a satisfactory total organic carbon (TOC) removal efficiency (67.8%), a stable component structure, and extremely low iron and molybdenum ion dissolution ( Figure 8 d). In addition, we used the Vibrio fischeri bioluminescence inhibition test to evaluate the toxicity of Cr(VI), BPA and their intermediates ( Figure 8 d) The results show that the Fe-MoS2HS / GF system produces very few toxic byproducts and significantly reduces their toxicity. This finding significantly reduces the risk of biotoxicity during the electrolysis process.

[0060] also, Figure 9The Fe-MoS2HS / GF system demonstrated excellent durability and recyclability during long-term cyclic operation (5 hours per cycle). The excellent performance of this system can be attributed to the improved crystallinity of MoS2 due to the introduction of iron, which enhanced the stability and reactivity of Fe-MoS2HS. Overall, the results highlight the ability of the Fe-Mo dual catalytic sites to maintain high levels of free radical generation and electrocatalytic redox activity. Therefore, the Fe-MoS2HS / GF system exhibits high efficiency and wide practical applicability in treating multi-component wastewaters.

Claims

1. An electro-Fenton system, comprising a metal anode and a cathode, wherein the cathode comprises graphite oxide felt loaded with iron-doped molybdenum disulfide microspheres, wherein the iron-doped molybdenum disulfide microspheres comprise nanosheet structures formed of iron, molybdenum, and sulfur, and wherein the Fe content in the iron-doped molybdenum disulfide microspheres is 0.5-4wt%.

2. The electro-Fenton system according to claim 1, wherein the Fe content in the iron-doped molybdenum disulfide microspheres is 1-2 wt%.

3. The electro-Fenton system according to claim 1, wherein the metal anode is a platinum electrode.

4. The electro-Fenton system according to claim 1, wherein the iron-doped molybdenum disulfide microspheres are formed by the following steps: dissolving ammonium molybdate and thiourea in water, adding Fe(NO3)3 solution, conducting a hydrothermal reaction at 200-240°C, separating the product by centrifugation, and drying it to finally obtain iron-doped molybdenum disulfide microspheres.

5. The electro-Fenton body system according to claim 1 further comprises a single-chamber electrolytic cell, a peristaltic pump and an air pump, wherein the peristaltic pump is used to deliver sewage into the single-chamber electrolytic cell, the air pump is used to deliver air to the air pump, and the metal anode and cathode are located in the single-chamber electrolytic cell.

6. A method for simultaneously removing heavy metals and organic pollutants from water, the method comprising treating water containing heavy metals and organic pollutants by the electro-Fenton system according to any one of claims 1 to 5. The method according to claim 6 , wherein the heavy metal comprises hexavalent chromium.

8. The method according to claim 6, wherein the organic pollutants include at least one of bisphenols, perfluorinated compounds, antibiotics, halogenated phenols and endocrine disruptors, or a combination of more than one of the group consisting of bisphenols, perfluorinated compounds, antibiotics, halogenated phenols and endocrine disruptors.

9. The method according to claim 6, wherein the water containing heavy metals and organic pollutants further contains chloride ions.

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