CoFe-LDO@CMS self-supporting electrode, capacitive deionization coupled electrocatalysis system and wastewater treatment method

Abstract

The application provides a CoFe-LDO@CMS self-supporting electrode, a capacitive deionization coupled electro-catalysis system and a wastewater treatment method, the CoFe-LDO@CMS self-supporting electrode comprises: carbonized melamine sponge CMS and cobalt-iron layered double metal oxide CoFe-LDO grown in situ on the carbonized melamine sponge CMS. The capacitive deionization coupled electro-catalysis system constructed by the CoFe-LDO@CMS self-supporting electrode can actively convert Cl ‑ into high-activity active chlorine species (RCS) when used for wastewater treatment containing organophosphonate and chloride ions, realizes efficient degradation and mineralization of organophosphonate, eliminates competitive ions and improves the solution environment, thereby greatly improving the selective adsorption and recovery efficiency of subsequent phosphate, and realizes the dual goals of "waste treatment with waste" and "resource recovery".

Description

Technical Field

[0001] This invention relates to the field of electrochemical wastewater treatment technology, and in particular to a CoFe-LDO@CMS self-supporting electrode, a capacitor deionization coupled electrocatalytic system, and a wastewater treatment method. Background Technology

[0002] Organophosphonates, such as aminotrimethylenephosphonic acid (ATMP) and hydroxyethylidene diphosphonic acid (HEDP), are widely used in industrial circulating cooling water, reverse osmosis pretreatment, oilfield extraction, and textile printing and dyeing industries due to their excellent chelating, corrosion inhibition, and scale inhibition properties. However, these compounds contain stable carbon-phosphorus (CP) bonds in their molecular structure, making them chemically stable and difficult to effectively degrade by traditional biological processes such as activated sludge. This leads to the continuous accumulation of organophosphonates in natural water bodies and industrial wastewater, posing a direct toxic threat to aquatic ecosystems. More importantly, they slowly degrade and release phosphate ions, becoming a potential endogenous source of pollution that induces eutrophication.

[0003] Even more challenging is that industrial processes that generate organophosphonate wastewater (such as circulating cooling water discharge and reverse osmosis concentrate) are typically accompanied by high concentrations of chloride ions (Cl). - ), forming Cl - Complex high-salt pollution systems coexisting with organophosphonates. High concentrations of Cl... - This not only increases the difficulty of biological treatment but also poses a severe challenge to physicochemical treatment processes. On the other hand, phosphorus is a non-renewable strategic resource with limited reserves and the risk of depletion globally. Therefore, the efficient degradation of organophosphonates from wastewater and the simultaneous recovery of phosphorus resources are of dual importance for water environmental protection and sustainable development.

[0004] To address the aforementioned challenges, advanced oxidation technologies (AOPs), particularly electrocatalytic advanced oxidation technologies (EAOPs), have shown great application potential due to their ability to generate highly oxidizing hydroxyl radicals (•OH) in situ. However, the efficiency of traditional electrocatalytic oxidation processes is often limited when treating organophosphonate wastewater with a high chlorine background. According to classical electrochemical theory, Cl... - Considered an effective quencher of •OH (Equation 1), it competes with the target pollutant for oxidants and may generate more toxic chlorinated byproducts. Therefore, it is generally regarded as a disadvantage, a perception that has largely limited the use of Cl... - Developing potential value.

[0005]

[0006] Meanwhile, capacitive deionization (CDI) technology has attracted widespread attention in the field of ion recovery due to its low energy consumption, flexible operation, and lack of secondary pollution. However, directly applying CDI to organophosphonate wastewater faces two fundamental bottlenecks: first, CDI can only remove ions through electrostatic adsorption and cannot break the CP bonds of organophosphonates, thus it cannot directly recover phosphorus in organic form; second, in the presence of Cl... - When competing anions coexist in large quantities, CDI has a greater effect on the phosphate group (H2PO4) of the target product. - / HPO4 2- The selective adsorption capacity of phosphorus is extremely poor, resulting in low phosphorus recovery efficiency and low product purity.

[0007] Recent research has provided us with new insights: on specific catalytic electrodes (such as Ti4O7 and transition metal oxide electrodes), Cl... - It can be electrochemically activated to generate active chlorine species (RCS), including chlorine gas (Cl2), hypochlorous acid (HClO), and chlorine radicals (Cl•), etc. (reactions 2-4). These RCS are highly efficient oxidants, capable of effectively attacking and breaking the stable CP bonds in organophosphonates, ultimately mineralizing them into inorganic phosphate, carbon dioxide, and water. This means that Cl... - Its role can be transformed from a "disruptor" to a "reinforcing medium".

[0008]

[0009] Although studies have been conducted on both RCS degradation of organic matter and CDI recovery of phosphates, this study aims to intentionally couple the two and systematically elucidate the role of Cl... - The core mechanism of action in the entire "degradation-recycling" chain still lacks technological understanding. Therefore, developing a method to remove "harmful" Cl from wastewater is crucial. - A new process that transforms the medium into a "favorable" oxidation medium and deeply couples it with a highly efficient phosphorus recovery unit is a key direction for solving the aforementioned industry pain points. Summary of the Invention

[0010] To address the technical problems existing in the background technology, this invention proposes a CoFe-LDO@CMS self-supporting electrode, a capacitor deionization coupled electrocatalytic system, and a wastewater treatment method. The capacitor deionization coupled electrocatalytic system constructed using the CoFe-LDO@CMS self-supporting electrode can actively remove Cl- from wastewater containing organophosphonates and chloride ions when used for wastewater treatment. -It is transformed into highly active chlorine species (RCS), which not only achieves efficient degradation and mineralization of organophosphonates, but also eliminates competing ions and improves the solution environment, thereby significantly improving the selective adsorption and recovery efficiency of subsequent phosphates and achieving the dual goals of "waste treatment" and "resource recovery".

[0011] This invention proposes a CoFe-LDO@CMS self-supporting electrode, comprising: a melamine sponge CMS and a cobalt-iron layered bimetallic oxide CoFe-LDO grown in situ on the surface of the melamine sponge CMS skeleton; The CoFe-LDO@CMS self-supporting electrode is prepared by in-situ growth of cobalt-iron layered bimetallic hydroxide from melamine sponge via hydrothermal reaction, followed by high-temperature carbonization under inert gas protection.

[0012] Preferably, in the cobalt-iron layered bimetallic oxide CoFe-LDO, the molar ratio of cobalt to iron is 2:1-4:1.

[0013] Preferably, the hydrothermal reaction includes: immersing a melamine sponge in a precursor solution containing iron salt, cobalt salt, ammonium fluoride and urea, and growing a cobalt-iron layered bimetallic hydroxide in situ through a hydrothermal reaction; The iron salt is at least one of ferric nitrate nonahydrate or ferric chloride hexahydrate, and the cobalt salt is at least one of cobalt nitrate hexahydrate or cobalt chloride hexahydrate.

[0014] In the specific operation, melamine sponge (MS) is washed and dried sequentially with acetone, ethanol, and deionized water. The dried MS is then immersed in a precursor solution containing cobalt salt, iron salt, ammonium fluoride, and urea. Cobalt-iron layered bimetallic hydroxide (CoFe-LDH) is grown in situ on the MS surface through a hydrothermal reaction to obtain the CoFe-LDH@MS composite material. The CoFe-LDH@MS composite material is then subjected to high-temperature carbonization under inert gas protection to convert CoFe-LDH into cobalt-iron layered bimetallic oxide (CoFe-LDO), while simultaneously carbonizing MS, ultimately obtaining the CoFe-LDO@CMS self-supporting electrode. MS without CoFe-LDO is carbonized under the same conditions to obtain the CMS self-supporting electrode.

[0015] Preferably, the hydrothermal reaction is carried out at a temperature of 100-140 ℃ for 4-8 h; the carbonization is carried out at a temperature of 350℃-700 ℃ for 1-2 h.

[0016] The present invention also proposes a capacitor deionization coupled electrocatalytic system, comprising: a capacitor deionization coupled electrocatalytic module; The capacitor deionization coupled electrocatalytic module is a sandwich structure of cathode / diaphragm / anode with baffles on both sides. The cathode is a carbonized melamine sponge CMS self-supporting electrode, and the anode is the CoFe-LDO@CMS self-supporting electrode mentioned above. The capacitor-deionized electrocatalytic module is used to simultaneously treat wastewater containing organophosphonates and chloride ions and to adsorb and recover phosphates.

[0017] In the specific operation process, the capacitor deionization coupled electrocatalytic module is arranged in the same direction, specifically in the following order: acrylic plate, silicone pad, cathode, silicone pad, diaphragm, anode, silicone pad, and acrylic plate.

[0018] Preferably, the system further includes: a power supply, a liquid storage tank, and a peristaltic pump; The power source is used to provide voltage to the capacitor deionization coupled electrocatalytic module; The peristaltic pump is used to draw wastewater from the storage tank through the capacitor deionization coupled electrocatalytic module and then recirculate it back into the storage tank.

[0019] In the specific operation, the power supply is used to apply voltage between the anode and the cathode; it also includes an aeration device, which is used to stabilize the dissolved oxygen concentration in the reaction system.

[0020] This invention also proposes a wastewater treatment method using the above-mentioned capacitor deionization coupled electrocatalytic system, comprising: using wastewater containing organophosphonates and chloride ions as the wastewater to be treated, transporting the wastewater to be treated in the storage tank to the capacitor deionization coupled electrocatalytic module for circulation via a peristaltic pump, wherein the capacitor deionization coupled electrocatalytic module degrades the organophosphonates in the wastewater to obtain phosphates and then simultaneously electro-adsorbs them, and then flows back to the storage tank, repeating the cycle until the electrodes reach an adsorption equilibrium state.

[0021] In the specific operation, wastewater containing organophosphonates and chloride ions with an appropriate pH value is introduced, and a certain voltage is applied. During the voltage application process, chloride ions are electrochemically activated at the anode to form active chloride species (RCS). The RCS oxidizes and decomposes organophosphonates, converting them into inorganic phosphate (PO4). 3- / HPO4 2- / H2PO4 - Meanwhile, the generated phosphate ions migrate under the influence of the electric field and are adsorbed by the charged electrode material, thereby achieving removal from the aqueous phase.

[0022] Preferably, the initial pH value of the wastewater to be treated is 3.0-11.0, the chloride ion concentration is 0-50 mM, and the concentration of organophosphonate is 10-100 mg / L; The organophosphonate is at least one of aminotrimethylenephosphonic acid (ATMP), ethylenediaminetetramethylenephosphonic acid (EDTMP), or hydroxyethylidene diphosphonic acid (HEDP).

[0023] Preferably, the operating voltage of the capacitor deionization coupled electrocatalytic module is 1.0-1.4V, and the flow rate of the wastewater to be treated is 5-20 mL / min.

[0024] Preferably, after the electrode reaches adsorption equilibrium, the method further includes: reversing the power supply or short-circuiting to desorb the phosphate, collecting the concentrate, and realizing phosphate recovery.

[0025] In the specific operation, when the electrode is saturated with adsorption, the applied voltage is reversed or set to zero, so that the phosphate ions adsorbed on the electrode are desorbed into the concentrate. The concentrate is then collected to obtain a phosphorus-rich solution, thus realizing the recovery of phosphate.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention breaks with the traditional concept of using Cl - Overcoming the preconceived notion that it is a "quencher" and "interference," this study designs a highly catalytically active CoFe-LDO@CMS anode to actively remove Cl, which is commonly found in wastewater. - Electrochemical conversion into highly oxidizing RCS is used to degrade recalcitrant organophosphonates; this "waste-to-waste" strategy transforms the original interfering factor into a highly efficient oxidizing medium, solving a major technical challenge in the treatment of high-chlorine wastewater.

[0027] (2) This invention is the first to use Cl - The activated electrocatalytic oxidation and capacitive deionization technology are intentionally and deeply coupled; the electrocatalytic oxidation layer (anodic function) is responsible for breaking CP bonds, realizing the conversion of organophosphorus to inorganic phosphorus, and simultaneously consuming competitive Cl. - The capacitor deionization layer (cathode function) is responsible for the efficient and selective recovery of released phosphate ions; the two processes are completed in the same reactor, which simplifies the process flow and reduces equipment investment and operating costs.

[0028] (3) Experimental data show that under optimal conditions (Co / Fe=2:1, voltage 1.4V, pH=7), the degradation efficiency of the system of the present invention for ATMP is as high as 88.98%, and the adsorption capacity of the phosphate generated by degradation reaches 21.51 mg P / g; compared with traditional AOPs (such as Fenton and persulfate systems), the degradation efficiency of the present invention is improved by 1.5-2.6 times; at the same time, due to Cl - When consumed at the anode, its competitive interference with phosphate adsorption at the cathode is significantly reduced, thus greatly improving the selectivity and purity of phosphate recovery.

[0029] (4) This invention, through free radical quenching experiments, quantitatively reveals for the first time the phenomenon of free radical quenching in Cl... - In the presence of Cl• and •OH, the degradation process is jointly dominated by Cl• and •OH, with Cl• contributing more than •OH. Furthermore, by adjusting the pH value (optimal pH=7) and monitoring H2O2 production, it was clarified that neutral conditions are most favorable for 2e-. - ORR generates H2O2, which in turn promotes the subsequent chain reaction mechanism of RCS formation and organophosphorus degradation. This provides a solid theoretical basis for process optimization.

[0030] (5) The CoFe-LDO@CMS electrode prepared by this invention has a three-dimensional porous structure, providing a large specific surface area and abundant active sites. After five cycles of use, the degradation efficiency of ATMP remains above 85%, demonstrating excellent stability and durability. Meanwhile, the raw materials, such as melamine sponge and cobalt / iron nitrate, are commercially available products with low cost and are easy to scale up.

[0031] (6) This invention is not only applicable to simulated ATMP wastewater, but also expected to have good treatment effects on other types of organic phosphonates such as HEDP and PBTCA, as well as complex matrices such as actual industrial circulating cooling water discharge and reverse osmosis concentrate by adjusting the operating parameters. It has broad application prospects. Attached Figure Description

[0032] Figure 1 The XRD patterns of CMS, CoFe-LDO1@CMS, CoFe-LDO2@CMS and CoFe-LDO3@CMS described in Example 1 of this invention; Figure 2 The following are SEM images of MS, CMS, and CoFe-LDO@CMS at different magnifications as described in Embodiment 1 of the present invention: (ac) is MS, (df) is CMS, and (gi) is CoFe-LDO@CMS; Figure 3 Fourier transform infrared spectra of CMS, CoFe-LDO1@CMS, CoFe-LDO2@CMS, and CoFe-LDO3@CMS as described in Embodiment 1 of the present invention; Figure 4 The results of removing organophosphates in a capacitive deionization coupled electrocatalytic system using different anode and cathode combinations in Example 2 of the present invention are as follows: (a) is the degradation rate of organophosphorus; (b) is the amount of phosphate adsorbed. Figure 5 Different Co values ​​in Embodiment 2 of the present invention 2+ / Fe 3+Results of using a CoFe-LDO@CMS self-supporting electrode with a molar ratio for the removal of organophosphonates in a capacitive deionization coupled electrocatalytic system: (a) residual organophosphonate; (b) amount of phosphate generated; (c) amount of phosphate adsorbed. Figure 6 The results of removing organophosphonates by the CoFe-LDO@CMS self-supporting electrode in the capacitive deionization coupled electrocatalytic system in Example 2 of this invention under different voltages are as follows: (a) is the residual rate of organophosphonates; (b) is the amount of phosphate generated; and (c) is the amount of phosphate adsorbed. Figure 7 The results of removing organophosphonates using the CoFe-LDO@CMS self-supporting electrode in the capacitive deionization coupled electrocatalytic system in Example 2 of this invention at different pH values ​​are as follows: (a) residual rate of organophosphonates; (b) amount of phosphate generated; (c) amount of phosphate adsorbed; (d) morphology of phosphate under different pH conditions; (e) isoelectric point of the CoFe-LDO@CMS self-supporting electrode; (f) amount of hydrogen peroxide generated under different pH conditions. Figure 8 The results of removing organophosphonates using the CoFe-LDO@CMS self-supporting electrode in the capacitive deionization coupled electrocatalytic system in Example 2 of this invention under different electrolyte conditions are as follows: (a) is the residual rate of organophosphonates; (b) is the amount of phosphate generated; and (c) is the amount of phosphate adsorbed. Figure 9 The results of removing organophosphonates using the CoFe-LDO@CMS self-supporting electrode in the capacitive deionization coupled electrocatalytic system in Example 2 of this invention at different sodium chloride concentrations are as follows: (a) is the residual rate of organophosphorus; (b) is the amount of phosphate generated; and (c) is the amount of phosphate adsorbed. Figure 10 The following are the free radical quenching results of the CoFe-LDO@CMS self-supporting electrode used in the capacitive deionization coupled electrocatalytic system for removing organophosphonates in Example 2 of this invention: (a) is the residual rate of organophosphonates; (b) is the degradation rate of organophosphonates. Figure 11 This is a comparison of the organophosphorus degradation performance of different systems in removing organophosphates in Example 2 of the present invention; Figure 12 The effect of the CoFe-LDO@CMS self-supporting electrode in Example 2 of the present invention on the removal of organophosphonates after 5 consecutive cycles in a capacitive deionization coupled electrocatalytic system is shown in Figure 2: (a) is the residual rate of organophosphonates; (b) is the amount of phosphate adsorbed. Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0034] Example 1 This embodiment proposes a CoFe-LDO@CMS self-supporting electrode and a CMS self-supporting electrode, and the specific preparation method includes: (1) CMS self-supporting electrode of carbonized melamine sponge: Commercial melamine sponge (MS) was cut into 2 cm × 3 cm × 0.3 cm pieces. After ultrasonic washing in acetone, ethanol and deionized water for 1 h to remove surface impurities, the MS was vacuum dried at 60 °C. The dried MS was then placed in a tube furnace and heated to 350 °C at a heating rate of 5 °C / min under N2 protection and held at that temperature for 1 h. After naturally cooling to room temperature, carbonized melamine sponge (CMS) was obtained. (2) CoFe-LDO@CMS self-supporting electrode of carbide melamine sponge loaded with cobalt-iron layered bimetallic oxide: Weigh out 0.87 g of Co(NO3)2·6H2O, 0.404 g of Fe(NO3)3·9H2O (Co / Fe molar ratio 3:1), 0.25 g of NH4F, and 1.2 g of urea, respectively, and dissolve them in 60 mL of deionized water. Stir with a strong magnetic stir at room temperature to form a transparent and homogeneous solution, which serves as the precursor solution. Immerse MS of the same size as in step (1) into the precursor solution and continue stirring for 1 h to ensure that the precursor solution fully penetrates and adsorbs onto the MS framework surface. Then, transfer the resulting mixture to a 100 mL stainless steel hydrothermal reactor lined with polytetrafluoroethylene, seal it, and place it in a 120 ℃ oven for 6 h. After the reaction, allow it to cool naturally to room temperature, remove the product, and rinse it repeatedly with anhydrous ethanol and deionized water to remove unreacted ions and physically adsorbed particles. Dry the resulting product in a 60 ℃ vacuum oven for 12 h. h, melamine sponge loaded with cobalt-iron layered bimetallic hydroxide (CoFe-LDH@MS) was obtained; then CoFe-LDH@MS was placed in a tube furnace and heated to 350 ℃ at a heating rate of 5 ℃ / min under N2 protection, and held at that temperature for 1 h. This process dehydrated the layered bimetallic hydroxide (LDH) and converted it into layered bimetallic oxide (LDO), while MS was carbonized and converted into CMS. After naturally cooling to room temperature, CoFe-LDO@CMS (CoFe-LDO2@CMS) self-supporting electrode of carbonized melamine sponge loaded with cobalt-iron layered bimetallic oxide was obtained.

[0035] In this embodiment, electrodes with other different carriers were also prepared. Specifically: referring to the preparation method of step (2), except that the MS was not immersed in the precursor solution, a CoFe-LDO electrode was obtained; referring to the preparation method of step (2), commercial activated carbon (AC) was used instead of MS to be immersed in the precursor solution, and a CoFe-LDO@AC electrode of commercial activated carbon loaded with cobalt-iron layered bimetallic oxide was obtained; referring to the preparation method of step (2), biochar (BC) was used instead of MS to be immersed in the precursor solution, and a CoFe-LDO@BC electrode of biochar loaded with cobalt-iron layered bimetallic oxide was obtained.

[0036] In this embodiment, other different Co samples were also prepared. 2+ / Fe 3+ The specific anode materials under the specified ratios are as follows: referring to the preparation method in step (2), except for weighing 0.58 g of Co(NO3)2·6H2O and controlling the Co / Fe molar ratio to 2:1, a CoFe-LDO1@CMS self-supporting electrode of carbonized melamine sponge loaded with cobalt-iron layered bimetallic oxide is obtained; referring to the preparation method in step (2), except for weighing 1.16 g of Co(NO3)2·6H2O and controlling the Co / Fe molar ratio to 4:1, a CoFe-LDO3@CMS self-supporting electrode of carbonized melamine sponge loaded with cobalt-iron layered bimetallic oxide is obtained.

[0037] Figure 1 The images show the XRD patterns of CMS, CoFe-LDO1@CMS, CoFe-LDO2@CMS (CoFe-LDO@CMS), and CoFe-LDO3@CMS described in Embodiment 1 of the present invention. (Refer to...) Figure 1 It can be seen that CMS and CoFe-LDO1@CMS, CoFe-LDO@CMS, and CoFe-LDO3@CMS all have a value of 23. o The presence of typical broad peaks characteristic of graphene on both sides indicates that CoFe-LDO@CMS and others retain the original properties of CMS; meanwhile, CoFe-LDO1@CMS, CoFe-LDO@CMS, and CoFe-LDO3@CMS all show peaks around 35.7. o And 62.3 o Diffraction peaks corresponding to the (311) and (440) crystal planes of CoFe-LDO appeared, but no CoFe-LDH peaks corresponding to the (003) crystal plane were observed, indicating that CoFe-LDO was successfully loaded onto its surface.

[0038] Example 2 This embodiment proposes a capacitor deionization coupled electrocatalytic system and a method for wastewater treatment using the capacitor deionization coupled electrocatalytic system, including: (1) Capacitor-deionized electrocatalytic system: The capacitor deionization coupled electrocatalytic system includes: a capacitor deionization coupled electrocatalytic module, a power supply, a storage tank, a peristaltic pump, and an aeration device; The capacitor deionization coupled electrocatalytic module consists of an acrylic plate, a silicone pad, a cathode, a silicone pad, a diaphragm, an anode, a silicone pad, and an acrylic plate, from left to right. Specifically, CoFe-LDO@CMS, CoFe-LDO@AC, and COFe-LDO@BC prepared in Example 1 are used as anodes, and CMS, AC, and BC are used as cathodes, respectively. An insulating diaphragm or spacer is placed between the two electrodes to prevent short circuits. The storage tank, peristaltic pump and capacitor deionization coupled electrocatalytic module are connected to form a circulation loop. The power supply is connected to the cathode and anode in the capacitor deionization coupled electrocatalytic module. The aeration device controls the dissolved oxygen. (2) Wastewater treatment method: Prepare simulated wastewater containing 10 mM NaCl (as electrolyte and Cl). - Simulated wastewater was pumped into the capacitor deionization coupled electrocatalytic module at a flow rate of 10 mL / min at room temperature, with 50 mg / L of ATMP (as the target organophosphonate) and 50 mg / L of ATMP (as the target organophosphonate). The initial pH was adjusted to 7.0. A voltage of 1.4 V was applied, and the charging (adsorption / oxidation) process lasted for 1 h. During this period, the phosphate concentration and total phosphorus concentration were measured from the water sample at regular intervals. After charging, the voltage was reversed or short-circuited, and discharge (desorption) was performed for 0.5 h. The concentrate was then collected.

[0039] (3) Performance evaluation: The total phosphorus concentration remaining in the solution per time (C TPt - The concentration of phosphate remaining in the solution per time (C) phosphatet = Remaining organic phosphorus concentration (C) t ), which is the organic phosphorus concentration at time t after wastewater treatment; Organophosphorus degradation efficiency Calculated by the following formula: Among them, C TP0 The initial total phosphorus concentration is denoted as C0; C t / C0 represents the residual rate of organophosphates.

[0040] Figure 4 The results of using different anode and cathode combinations (CMS / / CoFe-LDO, CMS / / CoFe-LDO@AC, CMS / / CoFe-LDO@BC, CMS / / CoFe-LDO@CMS, AC / / CoFe-LDO@CMS, BC / / CoFe-LDO@CMS) in a capacitive deionization coupled electrocatalytic system for the removal of organophosphates in Example 2 of this invention are shown. (Refer to...) Figure 4It was found that the organophosphorus degradation efficiency of CMS / CoFe-LDO without support was only 11.85%, while the organophosphorus degradation efficiencies of CMS / / CoFe-LDO@AC and CMS / / CoFe-LDO@BC, using activated carbon and biochar as supports respectively, increased to 34.34% and 45.13%, respectively. This indicates that the introduction of carbon supports can increase active sites and improve electron transport. Notably, the efficiency of BC / CoFe-LDO@CMS was 57.20%, but CMS / / CoFe-LDO@CMS exhibited the highest degradation efficiency, reaching 89.37%. In addition, CoFe-LDO@CMS also showed the largest adsorption capacity for phosphate (21.42 mg g / kg). -1 This significant improvement is attributed to the unique structural advantages of CMS: First, CMS possesses a three-dimensional interconnected porous network, which facilitates the rapid diffusion and enrichment of organophosphorus molecules; second, the nitrogen-doped carbon skeleton formed after melamine carbonization can modulate the local electronic structure, enhancing the interfacial synergistic effect with CoFe-LDO, thereby reducing the overpotential of electrocatalytic oxidation; furthermore, the high conductivity of CMS promotes charge transfer in the electrochemical reaction, and the tight composite between CMS and CoFe-LDO further exposes more catalytic active centers. These results demonstrate that using nitrogen-doped carbonized melamine sponge as a functional carrier can greatly enhance the electrocatalytic degradation performance of the CoFe-LDO system for organophosphorus compounds and its adsorption capacity for phosphates.

[0041] Figure 5 Different Co values ​​in Embodiment 2 of the present invention 2+ / Fe 3+ Results of using a CoFe-LDO@CMS self-supporting electrode with a molar ratio for the removal of organophosphates in a capacitive deionization coupled electrocatalytic system, refer to... Figure 5 It is evident that CoFe-LDH2@CMS exhibits the best performance, achieving a degradation rate of 89.37% for ATMP and a maximum adsorption capacity for the generated phosphate (21.42 mg P / g). This is because CoFe-LDH2@CMS has the highest crystallinity, which enhances charge transfer capabilities and thus improves its ATMP degradation performance. Conversely, excessively high LDO loading (CoFe-LDO3@CMS) may lead to nanoflower aggregation, while excessively low loading (CoFe-LDO@CMS) may expose part of the CMS framework. Both of these situations reduce the availability of active sites and ultimately decrease its performance. Therefore, CoFe-LDH2@CMS is the optimal anode material for ATMP degradation and phosphate recovery.

[0042] Figure 6This is the result of using a CoFe-LDO@CMS self-supporting electrode in Example 2 of the present invention to remove organophosphates under different voltages in a capacitive deionization coupled electrocatalytic system. (Refer to...) Figure 6 It can be seen that when the experiment of Example 2 was repeated at voltages of 1.0 V, 1.2 V and 1.4 V, as the voltage increased from 1.0 V to 1.4 V, the ATMP degradation efficiency significantly increased from 41.3% to 89.37%, and the phosphate adsorption capacity increased from 11.45 mg P / g to 21.42 mg P / g; however, when the voltage reached 1.6 V, the phosphate adsorption capacity decreased slightly due to the intensification of the oxygen evolution side reaction. Therefore, the optimal voltage is 1.4 V.

[0043] Figure 7 This is the result of using the CoFe-LDO@CMS self-supporting electrode in Example 2 of the present invention for the removal of organophosphates at different pH values ​​in a capacitive deionization coupled electrocatalytic system. (Refer to...) Figure 7 As can be seen from AC, when the experiment of Example 2 was repeated under pH conditions of 3.0, 5.0, 7.0, 9.0 and 11.0, the neutral pH condition of 7.0 was most favorable for system performance; refer to Figure 7 According to df, the isoelectric point of the electrode material is 5.56. When pH > 5.56, the electrode surface is positively charged, which is conducive to the electrostatic adsorption of negatively charged phosphate ions. In addition, neutral conditions are also most conducive to the generation of H2O2 (a precursor of reactive oxygen species). Therefore, the optimal initial pH is 7.0.

[0044] To verify Cl - The key roles and mechanisms of the study were verified, including: (1) Cl - The effect of concentration and electrolyte type: To investigate the influence of Cl - To understand its unique role in the reaction system, this study compared the treatment effects under different sodium salt electrolytes (10 mM). Figure 8 This is the result of using the CoFe-LDO@CMS self-supporting electrode in Example 2 of the present invention for the removal of organophosphates under different electrolyte conditions in a capacitive deionization coupled electrocatalytic system. (Refer to...) Figure 8 It can be seen that when NaF, NaNO3, NaCl, and Na2SO4 are used as electrolytes, the degradation efficiencies are 44.8%, 69.5%, 89.4%, and 81.6%, respectively; this indicates that Cl - The presence of [a specific substance] plays a key role in promoting the efficient degradation of ATMP; regarding phosphate adsorption, the influence of coexisting ions is as follows: F - SO4 2- NO3 - > Cl - , of which F - Due to strong electronegativity, SO42- strongly competes for adsorption sites.2- With the metal active sites (Fe) on the electrode surface 3+ Co 2+ Both exhibit strong affinity and significantly inhibit phosphate adsorption, while Cl... - It has the least negative impact on phosphate adsorption.

[0045] Figure 9 This is the result of using a CoFe-LDO@CMS self-supporting electrode in Example 2 of the present invention to remove organophosphates in a capacitive deionization coupled electrocatalytic system at different sodium chloride concentrations. (Refer to...) Figure 9 It can be seen that increasing chloride ion concentration promotes the degradation of ATMP and its conversion to phosphate; while for phosphate adsorption, Cl... - Further increases in concentration will compete with phosphate for adsorption sites on the electrode surface, thus reducing the adsorption performance for phosphate; therefore, Cl - The ATMP degradation and phosphate adsorption performance were best at a concentration of 10 mM.

[0046] (2) Free radical quenching experiment: To identify the dominant active species, tert-butanol (TBA, quenching •OH, Cl•, ClO•), nitrobenzene (NB, quenching •OH), and NaHCO3 (quenching Cl•) were added to the reaction system, respectively. The results are as follows: Figure 10 As shown, Figure 10 This is the free radical quenching experimental result of the CoFe-LDO@CMS self-supporting electrode used in the capacitive deionization coupled electrocatalytic system for the removal of organophosphates in Example 2 of this invention. (Refer to...) Figure 10 It can be seen that the degradation efficiency dropped sharply to 27.3% after the addition of TBA, indicating that free radicals are the main oxidizing agents; the degradation efficiency dropped to 72.78% after the addition of NaHCO3, and further to 83.3% after the addition of NB, indicating that Cl• and •OH both participate in the reaction, and that Cl• contributes more than •OH; this finding provides a basis for the degradation efficiency of Cl•. - It provides direct mechanistic evidence for its key role in the system.

[0047] To evaluate the superiority of the capacitor-deionization coupled electrocatalytic system (EC-CDI coupling system) constructed in this invention, its performance was compared with that of conventional advanced oxidation processes. The results... Figure 11 As shown, Figure 11 This is a comparison of the organophosphorus degradation performance of different systems in Example 2 of the present invention when removing organophosphates. (Refer to...) Figure 11 It can be seen that, within the same time frame, the CDI-EC coupling system achieves a degradation efficiency of up to 89.37% for ATMP, significantly higher than that of Fe. 2+ / H2O2 (34.49%), Fe 2+ / PMS (45.8%), CoFe-LDO@CMS / H2O2 (74.4%) and CoFe-LDO@CMS / PMS (58.6%) demonstrate the significant advantages of this coupling process in the degradation of organophosphonates.

[0048] Figure 12 To illustrate the effect of the CoFe-LDO@CMS self-supporting electrode in Example 2 of this invention on the removal of organophosphates after five consecutive cycles in a capacitive deionization coupled electrocatalytic system, refer to... Figure 12 It can be seen that after 5 cycles, the degradation efficiency of ATMP is still higher than 85%, and the adsorption of phosphate only decreases slightly, proving that the electrode material of the present invention has excellent long-term operational stability.

[0049] In summary, this invention not only provides a novel, efficient, stable, and recyclable technical solution for the treatment of recalcitrant organophosphonate wastewater and phosphorus resource recovery under high chlorine conditions, but more importantly, it systematically elucidates the role of Cl through functional electrode design and process coupling. - The role transformation and synergistic enhancement mechanism in the entire "degradation-recycling" chain provides a new technical path and theoretical basis for the paradigm shift of electrochemical water treatment technology from "single pollutant removal" to "synergistic degradation of pollutants and targeted resource recovery." Based on the above-mentioned outstanding advantages, this invention has broad application prospects and significant promotional value in the treatment of typical high-chlorine organophosphorus wastewater such as industrial circulating cooling water discharge, reverse osmosis concentrate, and oilfield produced water.

[0050] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A CoFe-LDO@CMS self-supporting electrode, characterized in that, include: Carbonized melamine sponge (CMS) and cobalt-iron layered bimetallic oxide (CoFe-LDO) grown in situ on the surface of the carbonized melamine sponge (CMS) skeleton; The CoFe-LDO@CMS self-supporting electrode is prepared by in-situ growth of cobalt-iron layered bimetallic hydroxide from melamine sponge via hydrothermal reaction, followed by high-temperature carbonization under inert gas protection. In the cobalt-iron layered bimetallic oxide CoFe-LDO, the molar ratio of cobalt to iron is 2:1-4:1; The hydrothermal reaction includes: immersing a melamine sponge in a precursor solution containing iron salt, cobalt salt, ammonium fluoride and urea, and growing a cobalt-iron layered bimetallic hydroxide in situ through a hydrothermal reaction; The iron salt is at least one of ferric nitrate nonahydrate or ferric chloride hexahydrate, and the cobalt salt is at least one of cobalt nitrate hexahydrate or cobalt chloride hexahydrate.

2. The CoFe-LDO@CMS self-supporting electrode according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 100-140 ℃ for 4-8 h; the carbonization is carried out at a temperature of 350 ℃-700 ℃ for 1-2 h.

3. A capacitor-deionized electrocatalytic system, characterized in that, include: Capacitor-deionized electrocatalytic module; The capacitor deionization coupled electrocatalytic module is a sandwich structure of cathode / diaphragm / anode with baffles on both sides, wherein the cathode is a carbonized melamine sponge CMS self-supporting electrode, and the anode is the CoFe-LDO@CMS self-supporting electrode as described in claim 1 or 2. The system is used for synchronous treatment of wastewater containing organophosphonate and chloride ions, and Cl - Electrochemical activation is active chlorine species to degrade organophosphonate, while the generated phosphate is adsorbed and degraded at the cathode.

4. The capacitor-deionization coupled electrocatalytic system according to claim 3, characterized in that, The system also includes: a power supply, a liquid storage tank, and a peristaltic pump; The power source is used to provide voltage to the capacitor deionization coupled electrocatalytic module; The peristaltic pump is used to draw wastewater from the storage tank through the capacitor deionization coupled electrocatalytic module and then recirculate it back into the storage tank.

5. A method for wastewater treatment using the capacitor deionization coupled electrocatalytic system as described in claim 3 or 4, characterized in that, include: The wastewater to be treated containing organophosphonate and chloride ions is passed into the capacitive deionization coupled electro-catalytic module, a voltage is applied, and the anode oxidizes the Cl - The electrochemical activation is an active chlorine species which oxidatively degrades the organophosphonate to generate phosphate ions; at the same time, the cathode captures the phosphate ions by electrostatic adsorption, and the cycle is processed until the electrode reaches adsorption equilibrium.

6. The wastewater treatment method using a capacitor-deionization coupled electrocatalytic system according to claim 5, characterized in that, The initial pH value of the wastewater to be treated is 3.0-11.0, the chloride ion concentration is 10-50 mM, and the concentration of organophosphonate is 10-100 mg / L; The organophosphonate is at least one of aminotrimethylenephosphonic acid (ATMP), ethylenediaminetetramethylenephosphonic acid (EDTMP), or hydroxyethylidene diphosphonic acid (HEDP).

7. The wastewater treatment method using a capacitor-deionization coupled electrocatalytic system according to claim 5 or 6, characterized in that, The operating voltage of the capacitor deionization coupled electrocatalytic module is 1.0-1.4V, and the flow rate of the wastewater to be treated is 5-20mL / min.

8. The wastewater treatment method using a capacitor deionization coupled electrocatalytic system according to claim 5 or 6, characterized in that, Once the electrode reaches adsorption equilibrium, the process also includes: reversing the power supply or short-circuiting to desorb the phosphate, collecting the concentrate, and recovering the phosphate.

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