A method for heavy metal removal based on the construction of a micro-electric field by synergistic ion confinement and metal self-corrosion

Abstract

This invention relates to a method for removing heavy metals based on a micro-electric field constructed using metal self-corrosion and synergistic ion confinement. The method includes the following steps: using a self-corroding metal as the anode, a copper-iron Prussian blue framework material electrode with an ion-confinement structure as the cathode, and heavy metal wastewater as the electrolyte to construct a micro-electric field with self-supplied energy characteristics; performing an electrochemical reaction to confine heavy metal ions within the cathode framework material, thereby achieving the removal of heavy metals from the wastewater. Compared with existing technologies, this invention, by constructing a micro-electric field with self-supplied energy characteristics, combined with a metal iron anode with a negative redox potential and a copper-iron Prussian blue cathode with an ion-confinement structure, achieves highly efficient and selective adsorption and stable solidification of heavy metal ions, without relying on an external power source or light source.

Description

Technical Field

[0001] This invention belongs to the field of environmental pollution control technology, and in particular relates to a method for removing heavy metals based on the construction of a micro-electric field by metal self-corrosion and synergistic ion confinement. Background Technology

[0002] The emissions of various pollutants during industrial production and urban and rural construction continue to rise, with the ecological security risks posed by heavy metal pollution being particularly prominent. Globally, approximately 20 million tons of heavy metal pollutants enter the environment annually through industrial wastewater and solid waste. Lead (Pb), cadmium (Cd), and mercury (Hg), among other typical heavy metals, pose serious threats to ecosystems and human health due to their strong biotoxicity, non-degradability, and bioaccumulation. Even more alarming is that these heavy metal pollutants can not only remain in the water and soil environment for decades but also amplify at each level of the food chain through bioaccumulation, ultimately threatening human health. Therefore, developing efficient and sustainable heavy metal pollution control technologies has become a crucial issue in the field of environmental protection.

[0003] In the field of heavy metal pollution control, traditional methods mainly rely on basic processes such as chemical precipitation, ion exchange, adsorption, and bioremediation. Chemical precipitation involves adding alkaline reagents to induce heavy metal ions to form hydroxides or sulfides, but its treatment efficiency is sensitive to pH control, and the large amount of precipitate produced requires subsequent hazardous waste solidification treatment. Ion exchange utilizes chelating resins for selective adsorption, but its regeneration efficiency decreases significantly with the number of cycles. Adsorption commonly uses materials such as activated carbon and zeolite, but their adsorption capacity is generally low, and the desorption and regeneration process carries the risk of secondary release of heavy metals. Bioremediation relies on specific microorganisms to fix heavy metals through bioreduction or extracellular polymeric binding, but its treatment cycle is long, and biological activity is significantly inhibited when the heavy metal concentration exceeds the microbial tolerance threshold.

[0004] In recent years, electrochemical technology has gradually become a research hotspot due to its advantages such as high selectivity, rapid response, and modular operation. However, existing research mostly focuses on external power sources or light source systems, which suffer from high energy consumption and cumbersome operation. For example, CN119954253A discloses a dual-pathway heavy metal fixation and removal method driven by a photoelectrochemical process. It utilizes a titanium dioxide electrode rich in oxygen vacancies as the photoanode and a copper-based Prussian blue framework material electrode with an ion-confined structure as the cathode. Through the synergistic effect of photogenerated electrons and holes, it achieves the oxidative fixation and ion intercalation fixation of heavy metal ions. However, this method still relies on an external light source to generate photoelectrons to participate in the electrochemical reaction, and it still cannot achieve the self-driven operation of the entire electrochemical system.

[0005] Therefore, a new method for heavy metal removal that is low-energy-consumption, sustainable, and self-driving still needs to be developed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies that rely on external light sources to generate photogenerated electrons to drive electrochemical reactions, and to provide a heavy metal removal method based on the construction of a micro-electric field by metal self-corrosion and ion confinement.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] This invention provides a method for removing heavy metals based on the construction of a micro-electric field through metal self-corrosion and synergistic ion confinement. The method includes the following steps:

[0009] A micro electric field with self-corroding properties is constructed by using a metal with self-corroding properties as the anode, a copper-iron Prussian blue framework material electrode with an ion-confined structure as the cathode, and heavy metal wastewater as the electrolyte.

[0010] An electrochemical reaction is then carried out to confine heavy metal ions within the cathode's framework material, thereby achieving the removal of heavy metals from the wastewater.

[0011] Furthermore, the metal with self-corrosion properties is any one or more alloys of iron, magnesium, zinc, and nickel.

[0012] Furthermore, all the metals possessing self-corrosion properties have negative redox potentials.

[0013] Furthermore, in the electrochemical reaction, the metal with self-corrosion properties continuously releases electrons to the cathode through the self-corrosion reaction, forming a spontaneous electrical circuit.

[0014] Furthermore, the copper-iron Prussian blue frame material is prepared using the following method:

[0015] S1: Add copper sulfate and potassium ferricyanide dropwise to deionized water, mix well, let stand for treatment, grind the precipitate to obtain CuFe PBA powder for later use.

[0016] S2: The CuFe PBA powder obtained in S1 is dispersed with superconducting carbon black and polyvinylidene fluoride in N-methylpyrrolidone solvent, and then ground evenly to obtain electrode slurry.

[0017] S3: The electrode paste obtained in S2 is uniformly coated on conductive carbon cloth and dried under vacuum to obtain a copper-iron Prussian blue framework material with an ion-confined structure.

[0018] Further, in step S1, the molar ratio of copper sulfate to potassium ferricyanide is 1:1.

[0019] Furthermore, in step S1, the particle size range of the CuFe PBA powder is 10–200 nm.

[0020] Further, in step S2, the mass ratio of CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride is (6-8):(1-3):1, preferably 7:2:1.

[0021] Furthermore, in step S2, the grinding time is 10 to 30 minutes.

[0022] Furthermore, in step S2, the total solids content in the electrode slurry is 75-85 wt%.

[0023] Further, in step S3, the coating amount of the electrode paste is 1–50 mg / cm³. -2 .

[0024] Furthermore, in step S3, the temperature of the vacuum drying is 60–100°C.

[0025] Furthermore, in step S3, the vacuum drying time is 16–20 hours.

[0026] Furthermore, the heavy metal elements in the heavy metal wastewater include any one or more of lead, cadmium, and mercury.

[0027] This invention proposes a method for removing heavy metal ions from groundwater based on a micro-electric field constructed using metal self-corrosion and synergistic ion confinement. This method achieves highly efficient and selective adsorption and stable solidification of heavy metal ions by designing a micro-electric field with self-supplied energy, combined with a metal iron anode with a negative redox potential and a copper-iron Prussian blue (CuFe PBA) cathode with an ion-confining structure. During system operation, the metal iron anode undergoes a self-corrosion reaction (Fe(O) → Fe(II) + 2e⁻)… - The CuFe continuously releases electrons to the cathode, forming a spontaneous and stable electrical circuit that can drive the electrochemical reaction without an external power source. The CuFe PBA terminal accepts electrons (Fe(III) + e- → Fe(II)), which fixes and removes heavy metal ions through an ion confinement pathway, significantly improving the heavy metal removal efficiency.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The heavy metal removal method of the present invention constructs an innovative micro electric field with self-supplied energy characteristics, and combines a metal iron anode with negative redox potential with a copper iron Prussian blue cathode with ion confinement structure. It can achieve efficient and selective adsorption and stable solidification of heavy metal ions in a self-driven manner, without relying on external power source or light source.

[0030] (2) In the process of system operation, the heavy metal removal method of the present invention provides electrons to the electrochemical system through self-corrosion of the metal anode and accepts electrons from the cathode. The heavy metal ions are fixed and removed through the ion confinement path. The synergistic effect of metal self-corrosion and ion confinement significantly improves the heavy metal removal efficiency, effectively curbs secondary environmental risks, and provides an environmentally friendly solution for the treatment of heavy metal pollution. It has both significant environmental and economic benefits.

[0031] (3) The micro electric field construction of the present invention relies on the self-corrosion of the anode for energy supply. The process is green and environmentally friendly. Compared with the high energy consumption mode of traditional electrochemical treatment technology that relies on external power supply, it has the advantages of mild reaction conditions, controllable operating costs, and easy large-scale application. It provides a new low-energy solution for the removal of heavy metal pollution, and at the same time shows considerable environmental benefits and resource recycling value. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the principle of the heavy metal removal method of the present invention.

[0033] Figure 2 This is a diagram showing the removal effect of simulated heavy metal wastewater at different concentrations in Example 1 of the present invention.

[0034] Figure 4 The diagram shows the effect of heavy metal wastewater removal at different times in Embodiment 1 of the present invention.

[0035] Figure 3 This is a diagram illustrating the simulated heavy metal wastewater removal effect of Embodiment 2 of the present invention. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0037] This invention provides a method for removing heavy metals based on a micro-electric field constructed by metal self-corrosion and synergistic ion confinement. The method includes the following steps: using a metal with self-corrosion properties as the anode, a copper-iron Prussian blue frame material electrode with an ion confinement structure as the cathode, and heavy metal wastewater as the electrolyte to construct a micro-electric field with self-supplied energy characteristics; performing an electrochemical reaction to confine heavy metal ions within the cathode frame material, thereby achieving the removal of heavy metals from the wastewater.

[0038] In some specific embodiments, the metal with self-corrosion properties is any one or more alloys of iron, magnesium, zinc, and nickel, such as using iron, magnesium, zinc, or nickel alone, or alloys of the above metals.

[0039] In some specific embodiments, the metals possessing self-corrosion properties all have negative redox potentials. The redox potentials are: iron (-0.44V vs. SHE), zinc (-0.76V vs. SHE), and nickel (-0.23V vs. SHE).

[0040] In some specific embodiments, during the electrochemical reaction, the metal with self-corrosion properties continuously releases electrons to the cathode through a self-corrosion reaction, forming a spontaneous electrical circuit.

[0041] In some specific embodiments, the copper-iron Prussian blue frame material is prepared by the following method:

[0042] S1: Add copper sulfate and potassium ferricyanide dropwise to deionized water, mix well, let stand for treatment, grind the precipitate to obtain CuFe PBA powder for later use.

[0043] S2: The CuFe PBA powder obtained in S1 is dispersed with superconducting carbon black and polyvinylidene fluoride in N-methylpyrrolidone solvent, and then ground evenly to obtain electrode slurry.

[0044] S3: The electrode paste obtained in S2 is uniformly coated on conductive carbon cloth and dried under vacuum to obtain a copper-iron Prussian blue framework material with an ion-confined structure.

[0045] In some specific embodiments, in step S1, the molar ratio of copper sulfate to potassium ferricyanide is 1:1.

[0046] In some specific embodiments, in step S1, the particle size range of the CuFe PBA powder is 10–200 nm.

[0047] In some specific embodiments, in step S2, the mass ratio of CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride is (6-8):(1-3):1, for example 6:1:1, 7:2:1, 8:3:1, preferably 7:2:1.

[0048] In some specific embodiments, the grinding time in step S2 is 10 to 30 minutes, such as 10 minutes, 20 minutes, or 30 minutes.

[0049] In some specific embodiments, in step S2, the total solids content in the electrode slurry is 75-85 wt%.

[0050] In some specific embodiments, in step S3, the coating amount of the electrode paste is 1–50 mg / cm³. -2 , such as 1mg cm -2 10mg cm-2 20mg cm -2 50mg cm -2 .

[0051] In some specific embodiments, in step S3, the temperature of the vacuum drying is 60 to 100°C, such as 60°C, 70°C, 80°C, 90°C, or 100°C.

[0052] In some specific implementations, the vacuum drying time in step S3 is 16 to 20 hours, such as 16 hours, 18 hours, or 20 hours.

[0053] In some specific embodiments, the heavy metal elements in the heavy metal wastewater include any one or more of lead, cadmium, and mercury.

[0054] Each of the above embodiments can be implemented individually, or in any combination of two or more. The following detailed description of specific examples will further illustrate these embodiments.

[0055] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0056] Example 1:

[0057] This embodiment provides a method for removing heavy metal ions from groundwater based on a micro-electric field constructed by metal self-corrosion and synergistic ion confinement, including the following steps:

[0058] like Figure 1 As shown, in this embodiment, self-corroding metallic iron is selected as the anode, and a copper-iron Prussian blue electrode with an ion-confined structure is used as the cathode. The anode and cathode are placed in an electrolyte. Heavy metal wastewater (lead nitrate solution is used as an example to simulate heavy metal wastewater) is used as the electrolyte. Heavy metal ions are confined within the framework of the cathode (the anode undergoes a self-corrosion mechanism, with zero-valent iron self-corroding to divalent iron, Fe(III) + e-). - →Fe(II), continuously releasing electrons to the cathode, which accepts the electrons and removes heavy metal ions through the ion insertion pathway, thereby achieving the removal of heavy metals from heavy metal wastewater.

[0059] Specifically, the preparation method of the copper-iron Prussian blue electrode with ion-confined structure in this embodiment includes the following steps:

[0060] (1) Add 20 mL of 0.05 mol L -1 Copper sulfate solution and 20 mL of 0.05 mol / L... -1Potassium ferricyanide solution was added dropwise to 100 mL of deionized water. After mixing with magnetic stirring for 0.5 h, the mixture was allowed to stand for 24 h. The resulting precipitate was centrifuged, washed, dried, and then ground to obtain CuFe PBA powder.

[0061] (2) Disperse 49 mg of CuFe PBA powder obtained in step (1) with 14 mg of superconducting carbon black and 7 mg of polyvinylidene fluoride in 1 mL of N-methylpyrrolidone solvent, grind for 10 min to obtain electrode slurry.

[0062] (3) The electrode paste obtained in step (2) is uniformly coated onto the pretreated conductive carbon cloth (coating amount is 50 mg cm). -2 After vacuum drying (temperature 100℃, time 18h), a copper-iron Prussian blue electrode with an ion-confined structure was obtained.

[0063] Example 2:

[0064] This embodiment provides a method for removing heavy metal ions from groundwater by constructing a micro-electric field based on metal self-corrosion synergistic ion confinement. The difference from Embodiment 1 is that the anode in this embodiment is selected as magnesium metal with self-corrosion properties, and the preparation of the copper-iron Prussian blue electrode is the same as in Embodiment 1.

[0065] Example 3:

[0066] This embodiment provides a method for removing heavy metal ions from groundwater by constructing a micro-electric field based on metal self-corrosion synergistic ion confinement. The difference from Embodiment 1 is that the anode in this embodiment is selected as zinc metal with self-corrosion properties, and the preparation of the copper-iron Prussian blue electrode is the same as in Embodiment 1.

[0067] Example 4:

[0068] This embodiment provides a method for removing heavy metal ions from groundwater by constructing a micro-electric field based on metal self-corrosion synergistic ion confinement. The difference from Embodiment 1 is that the anode in this embodiment is selected as nickel metal with self-corrosion properties, and the preparation of the copper-iron Prussian blue electrode is the same as in Embodiment 1.

[0069] This invention uses simulated heavy metal wastewater containing lead nitrate as an electrolyte to test the removal efficiency of the above method for heavy metal ions at different heavy metal concentrations and time periods.

[0070] This invention uses simulated heavy metal wastewater (10-1000 mg / L) -1 Using lead nitrate solution as the electrolyte, heavy metal ions are confined within the cathode framework (the anode, through a self-corrosion mechanism, corrodes zero-valent iron to divalent iron, continuously releasing electrons to the cathode, which accepts electrons and removes heavy metal ions through ion intercalation pathways), thus achieving the removal of heavy metals from heavy metal wastewater.

[0071] The water sample taken in the experiment was diluted and detected using inductively coupled plasma optical emission spectrometry (ICP-OES) to obtain the solution concentration. The lead ion fixation rate and lead ion fixation percentage were then calculated using the following formulas.

[0072]

[0073]

[0074] Example 1 uses iron as the anode metal, and the removal results of the heavy metal lead are as follows: Figure 2 As shown. At 50 mg / L -1 In a lead nitrate solution, the lead ion fixation rate can reach 37.5% after 30 minutes, at a concentration of 1000 mg / L. -1 The lead ion fixation rate in lead nitrate solution can reach 372.6 mg / L within 5 minutes. -1 h -1 Furthermore, in low-concentration simulated heavy metal wastewater (10 mg / L)... -1 In tests conducted at different time intervals (5–60 min) using lead nitrate solution, the removal results of Example 1 with iron as the anode metal are as follows: Figure 3 As shown, at 10 mg L -1 The fixation rate in lead nitrate solution can reach 20.92 mg / L in 5 minutes. -1 h -1 The fixation rate can reach 81.38% in 60 minutes, demonstrating excellent heavy metal lead removal effect.

[0075] Example 2 uses magnesium as the anode metal, and the removal results of the heavy metal lead are as follows: Figure 3 As shown, at 1000 mg L -1 In lead nitrate solution, the fixation rate of lead ions reached 86.4% after 30 minutes, and the fixation rate of lead ions reached 4461 mg / L after 5 minutes of experiment. -1 h -1 .

[0076] In Examples 3 and 4, zinc and nickel were used as anode metals, respectively, and both showed excellent removal effects on the heavy metal lead.

[0077] This invention proposes a method for removing heavy metal ions from groundwater based on a micro-electric field constructed using metal self-corrosion and synergistic ion confinement. This method achieves highly efficient and selective adsorption and stable solidification of heavy metal ions through the design of a micro-electric field with self-supplied energy, combined with a metal iron anode with a negative redox potential and a copper-iron Prussian blue (CuFe PBA) cathode with an ion-confining structure. During system operation, the metal anode undergoes a self-corrosion reaction (taking iron as an example, Fe(O) → Fe(II) + 2e⁻) to remove heavy metal ions.- The process continuously releases electrons to the cathode, forming a spontaneous and stable electrical circuit that drives the electrochemical reaction without the need for an external power source. The CuFe PBA terminal accepts electrons (e.g., Fe(III) + e- → Fe(II)), immobilizing and removing heavy metal ions through an ion-confined pathway, significantly improving heavy metal removal efficiency. This invention not only improves the removal efficiency of heavy metal ions but also effectively curbs secondary environmental risks, providing an environmentally friendly solution for heavy metal pollution control, with significant environmental and economic benefits.

[0078] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for removing heavy metals based on a micro-electric field constructed by synergistic ion confinement and metal self-corrosion, characterized in that, The heavy metal removal method includes the following steps: Using a self-corroding metal as the anode, a copper-iron Prussian blue framework material electrode with an ion-confining structure as the cathode, and heavy metal wastewater as the electrolyte, a micro electric field with self-supplied energy is constructed; then an electrochemical reaction is carried out to confine heavy metal ions in the framework material of the cathode, thereby achieving the removal of heavy metals from the wastewater. The metal with self-corrosion properties is any one or more alloys of iron, magnesium, zinc, and nickel; The copper-iron Prussian blue frame material is prepared by the following method: S1: Add copper sulfate and potassium ferricyanide dropwise to deionized water, mix well, let stand for treatment, grind the precipitate to obtain CuFe PBA powder for later use. S2: The CuFe PBA powder obtained in S1 is dispersed with superconducting carbon black and polyvinylidene fluoride in N-methylpyrrolidone solvent, and then ground evenly to obtain electrode slurry. S3: The electrode paste obtained in S2 is uniformly coated on conductive carbon cloth and dried under vacuum to obtain a copper-iron Prussian blue framework material with an ion-confined structure.

2. The heavy metal removal method based on the construction of a micro-electric field by synergistic ion confinement and metal self-corrosion as described in claim 1, characterized in that, The metals possessing self-corrosion properties all have negative redox potentials; In the electrochemical reaction, the metal with self-corrosion properties continuously releases electrons to the cathode through the self-corrosion reaction, forming a spontaneous electrical circuit.

3. The heavy metal removal method based on the construction of a micro-electric field by synergistic ion confinement and metal self-corrosion as described in claim 1, characterized in that, In step S1, the molar ratio of copper sulfate to potassium ferricyanide is 1:1; The CuFe PBA powder has a particle size range of 10~200 nm.

4. The heavy metal removal method based on the construction of a micro-electric field by synergistic ion confinement and metal self-corrosion as described in claim 1, characterized in that, In step S2, the mass ratio of CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride is (6~8): (1~3):

1.

5. The method for heavy metal removal based on the construction of a micro-electric field by synergistic ion confinement and metal self-corrosion according to claim 1, characterized in that, In step S2, the grinding time is 10~30 min; The total solids content in the electrode slurry is 75-85 wt%.

6. The heavy metal removal method based on the construction of a micro-electric field by synergistic ion confinement and metal self-corrosion according to claim 1, characterized in that, In step S3, the coating amount of the electrode paste is 1~50 mg·cm⁻¹. -2 .

7. The method for heavy metal removal based on the construction of a micro-electric field by synergistic ion confinement and metal self-corrosion according to claim 1, characterized in that, In step S3, the vacuum drying temperature is 60~100 ℃ and the time is 16~20 h.

8. The method for heavy metal removal based on the synergistic ion confinement construction of a micro-electric field by metal self-corrosion according to claim 1, characterized in that, The heavy metal elements in the heavy metal wastewater include any one or more of lead, cadmium, and mercury.

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