Heavy metal removal method for constructing micro electric field based on cooperation of metal self-corrosion and ion confinement

Abstract

The invention relates to a heavy metal removal method for constructing a micro electric field based on cooperation of metal self-corrosion and ion confinement. The heavy metal removal method comprises the following steps that metal with self-corrosion performance serves as an anode, a copper-iron Prussian blue frame material electrode with an ion confinement structure serves as a cathode, heavy metal wastewater serves as electrolyte, and a micro electric field with the energy self-supply characteristic is constructed; and carrying out electrochemical reaction to limit the heavy metal ions in the cathode framework material so as to remove the heavy metal in the wastewater. Compared with the prior art, by constructing the micro electric field with the energy self-supply characteristic and combining the metal iron anode with the negative oxidation-reduction potential and the copper-iron Prussian blue cathode with the ion confinement structure, efficient selective adsorption and stable curing of the heavy metal ions are achieved, and dependence on an external power source or a light source is not needed.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental pollution control, and in particular relates to a heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field. Background Art

[0002] The emission of various pollutants in the process of industrial production and urban and rural construction continues to rise, among which the ecological safety risks caused by heavy metal pollution are particularly prominent. About 20 million tons of heavy metal pollutants enter the environmental system through industrial wastewater, solid waste and other channels every year. Among them, typical heavy metals such as lead (Pb), cadmium (Cd), and mercury (Hg) pose a serious threat to the ecosystem and human health due to their strong biological toxicity, non-degradability and bioaccumulation. What is more serious is that these heavy metal pollutants can not only remain in the water and soil environment for decades, but also be amplified step by step in the food chain through the bioaccumulation effect, ultimately threatening human health. Therefore, the development of heavy metal pollution control technologies that are both efficient and sustainable has become an important issue in the field of environmental protection.

[0003] In the field of heavy metal pollution control, traditionally, basic processes such as chemical precipitation, ion exchange, adsorption and bioremediation have been relied upon. Chemical precipitation involves adding alkaline reagents to induce heavy metal ions to form hydroxide or sulfide precipitates, but its treatment efficiency is sensitive to pH regulation, and the large amount of precipitates produced subsequently requires hazardous waste solidification treatment. The ion exchange method can utilize chelating resins to achieve selective adsorption, and the regeneration efficiency will also significantly decrease with the number of cycles. Adsorption methods often use materials such as activated carbon and zeolite, but their adsorption capacity is generally low, and there is a risk of secondary release of heavy metals during the desorption and regeneration process. Bioremediation relies on specific microorganisms to fix heavy metals through biological reduction or extracellular polymer binding, but its treatment cycle is long, and when the heavy metal concentration exceeds the microbial tolerance threshold, the biological activity will be significantly inhibited.

[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 focuses on external power supply or light source system, which has the problems of high energy consumption and cumbersome operation. For example, CN119954253A discloses a dual-path heavy metal fixation and removal method driven by photoelectrochemical process, which uses a titanium dioxide electrode rich in oxygen vacancies as a photoanode and a copper-based Prussian blue framework material electrode with an ion confinement structure as a cathode, and realizes the oxidation fixation and ion embedding fixation of heavy metal ions through the synergistic effect of photogenerated electrons and holes. However, this method still needs to rely on an external light source to generate photogenerated electrons to participate in the electrochemical reaction, and still cannot achieve the self-driven operation of the entire electrochemical system.

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

[0006] The purpose of the present invention is to overcome the defect of the existing technology that it needs to rely on external light sources to generate photogenerated electrons to promote electrochemical reactions and to provide a heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field, the heavy metal removal method comprising the following steps:

[0009] A self-corroding metal is used as the anode, a copper-iron-Prussian blue framework material electrode with an ion-confined structure is used as the cathode, and heavy metal wastewater is used as the electrolyte to construct a micro-electric field with energy self-supply characteristics.

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

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

[0012] Furthermore, the metals with self-corrosion properties all 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 by the following method:

[0015] S1: copper sulfate and potassium ferrocyanide are added dropwise to deionized water, mixed and allowed to stand, and the precipitate is ground to obtain CuFe PBA powder for later use;

[0016] S2: Disperse the CuFe PBA powder prepared in S1, superconducting carbon black, and polyvinylidene fluoride in N-methylpyrrolidone solvent, and grind them evenly to obtain electrode slurry;

[0017] S3: The electrode slurry obtained in S2 is evenly coated on a conductive carbon cloth, and after vacuum drying, a copper-iron Prussian blue framework material with an ion-confined structure is obtained.

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

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

[0020] Furthermore, in step S2, the mass ratio of the 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 solid content of the electrode slurry is 75-85 wt%.

[0023] Furthermore, in step S3, the coating amount of the electrode slurry is 1 to 50 mg cm -2 .

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

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

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

[0027] The present invention proposes a method for removing heavy metal ions from groundwater by constructing a micro-electric field based on metal self-corrosion and ion confinement. This method achieves efficient selective adsorption and stable solidification of heavy metal ions by designing a micro-electric field with energy self-supply characteristics, combining a metal iron anode with a negative redox potential and a copper iron Prussian blue (CuFe PBA) cathode with an ion confinement structure. During the operation of the system, the metal iron anode undergoes a self-corrosion reaction (Fe(0)→Fe(II)+2e - ) 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 end accepts electrons (Fe(III) + e- → Fe(II)), removing heavy metal ions through an ion-confined pathway, significantly improving 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-energy supply characteristics, combines a metal iron anode with a negative redox potential and a copper-iron Prussian blue cathode with an ion-confined structure, and can self-drive to achieve efficient selective adsorption and stable solidification of heavy metal ions without relying on external power or light source.

[0030] (2) During the operation of the heavy metal removal method of the present invention, the metal anode provides electrons for the electrochemical system through self-corrosion, and the cathode accepts electrons and removes heavy metal ions through the ion confinement path. The synergistic cooperation of metal self-corrosion and ion confinement significantly improves the efficiency of heavy metal removal, effectively curbs secondary environmental risks, and provides an environmentally friendly solution for heavy metal pollution control, with 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, and 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the principle of the heavy metal removal method of the present invention.

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

[0034] Figure 4 This is a diagram showing the removal effect of heavy metal wastewater at different times according to Example 1 of the present invention.

[0035] Figure 3 This is a diagram showing the effect of simulated heavy metal wastewater removal in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0037] The present invention provides a heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field. The heavy metal removal method comprises the following steps: using a metal with self-corrosion properties as an anode, a copper-iron-Prussian blue framework material electrode with an ion confinement structure as a cathode, and heavy metal wastewater as an electrolyte to construct a micro-electric field with energy self-supply characteristics; performing an electrochemical reaction to confine heavy metal ions in the cathode framework material, thereby achieving heavy metal removal in the wastewater.

[0038] In some specific embodiments, the metal with self-corrosion properties is an alloy of any one or more of iron, magnesium, zinc, and nickel, for example, iron, magnesium, zinc, and nickel are used alone, or in the form of alloys of the above metals.

[0039] In some specific embodiments, the metals having self-corrosion properties all have negative redox potentials, such as the redox potential of metallic iron (-0.44 V vs. SHE), the redox potential of metallic zinc (-0.76 V vs. SHE), and the redox potential of metallic nickel (-0.23 V vs. SHE).

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

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

[0042] S1: copper sulfate and potassium ferrocyanide are added dropwise to deionized water, mixed and allowed to stand, and the precipitate is ground to obtain CuFe PBA powder for later use;

[0043] S2: Disperse the CuFe PBA powder prepared in S1, superconducting carbon black, and polyvinylidene fluoride in N-methylpyrrolidone solvent, and grind them evenly to obtain electrode slurry;

[0044] S3: The electrode slurry obtained in S2 is evenly coated on a conductive carbon cloth, and after vacuum drying, a copper-iron Prussian blue framework material with an ion-confined structure is obtained.

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

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

[0047] In some specific embodiments, in step S2, the mass ratio of the 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, in step S2, the grinding time is 10 to 30 minutes, such as 10 minutes, 20 minutes, or 30 minutes.

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

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

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

[0052] In some specific embodiments, in step S3, the vacuum drying time 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] The above embodiments can be implemented individually or in any combination of two or more. The above embodiments will be described in more detail below with reference to specific examples.

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

[0056] Example 1:

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

[0058] like Figure 1 As shown, this embodiment selects self-corroding metallic iron as the anode, and a copper-iron Prussian blue electrode with an ion-confined structure 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, and heavy metal ions are confined in the framework of the cathode (the anode self-corrodes through the mechanism of self-corrosion, and zero-valent iron self-corrodes to divalent iron, Fe(III)+e - →Fe(II), continuously releases electrons to the cathode, the cathode accepts electrons, and removes heavy metal ions through the ion embedding path), thereby achieving the removal of heavy metals in heavy metal wastewater.

[0059] Specifically, the preparation method of the copper-iron Prussian blue electrode with an 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 ferrocyanide solution was added dropwise to 100 mL of deionized water, mixed by magnetic stirring for 0.5 h, and then allowed to stand for 24 h. The resulting precipitate was centrifuged, washed, dried, and then ground to obtain CuFe PBA powder;

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

[0062] (3) The electrode slurry obtained in step (2) was evenly coated on the pretreated conductive carbon cloth (the coating amount was 50 mg cm -2 ), and after vacuum drying (temperature 100°C, 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 in groundwater by constructing a micro-electric field based on metal self-corrosion and cooperative ion confinement. The difference from Example 1 is that the anode of this embodiment is made of metal magnesium with self-corrosion properties, and the preparation of the copper-iron Prussian blue electrode refers to Example 1.

[0065] Example 3:

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

[0067] Example 4:

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

[0069] The present invention uses simulated heavy metal wastewater containing lead nitrate as electrolyte to test the heavy metal ion removal effect of the above method at different heavy metal concentrations and different time periods.

[0070] The present invention simulates heavy metal wastewater (10-1000 mg L -1 The lead nitrate solution is used as the electrolyte, and the heavy metal ions are confined in the framework of the cathode (the anode uses the self-corrosion mechanism, the zero-valent iron corrodes into divalent iron, continuously releasing electrons to the cathode, and the cathode accepts electrons and removes heavy metal ions through the ion embedding path), thereby realizing the removal of heavy metals in heavy metal wastewater.

[0071] The water samples were diluted and analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES) to determine the solution concentration. The lead ion fixation rate and lead ion fixation ratio were then calculated using the following formula.

[0072]

[0073]

[0074] Example 1 uses iron as the anode metal, and the removal results of heavy metal lead are as follows: Figure 2 As shown. At 50 mg L -1 The fixation rate of lead ions in the lead nitrate solution can reach 37.5% in 30 minutes. -1 The lead ion fixation rate in lead nitrate solution can reach 372.6 mg L within 5 min. -1 h -1 In addition, in low concentration simulated heavy metal wastewater (10 mg L -1 In the test of different time periods (5 to 60 min) of lead nitrate solution, the removal results of Example 1 using 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 min. -1 h -1 , the fixation rate can reach 81.38% in 60 minutes, showing an excellent heavy metal lead removal effect.

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

[0077] The present invention proposes a method for removing heavy metal ions from groundwater by constructing a micro-electric field based on metal self-corrosion and ion confinement. This method realizes the efficient selective adsorption and stable solidification of heavy metal ions in a self-driven manner by designing a micro-electric field with energy self-supply characteristics, combining a metal iron anode with a negative redox potential and a copper iron Prussian blue (CuFe PBA) cathode with an ion confinement structure. During the operation of the system, the metal anode undergoes a self-corrosion reaction (for example, Fe(0)→Fe(II)+2e- ) continuously releases electrons to the cathode, forming a spontaneous and stable electrical circuit, which can drive the electrochemical reaction without an external power supply. The CuFe PBA end accepts electrons (such as Fe(III)+e-→Fe(II)), and removes heavy metal ions through an ion confinement path, significantly improving the heavy metal removal efficiency. The present 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, and has significant environmental and economic benefits.

[0078] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. 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 present invention, should be within the scope of protection of the present invention.

Claims

1. A heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field, characterized in that: The heavy metal removal method comprises the following steps: A self-corroding metal is used as the anode, a copper-iron-Prussian blue framework material electrode with an ion-confined structure is used as the cathode, and heavy metal wastewater is used as the electrolyte to construct a micro-electric field with energy self-supply characteristics. An electrochemical reaction is then carried out to confine the heavy metal ions in the framework material of the cathode, thereby achieving the removal of heavy metals in the wastewater.

2. The heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field according to claim 1, characterized in that: The metal with self-corrosion properties is an alloy of any one or more of iron, magnesium, zinc and nickel.

3. The heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field according to claim 1, characterized in that: The metals having 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.

4. The heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field according to claim 1, characterized in that: The copper-iron Prussian blue frame material is prepared by the following method: S1: copper sulfate and potassium ferrocyanide are added dropwise to deionized water, mixed and allowed to stand, and the precipitate is ground to obtain CuFe PBA powder for later use; S2: Disperse the CuFe PBA powder prepared in S1, superconducting carbon black, and polyvinylidene fluoride in N-methylpyrrolidone solvent, and grind them evenly to obtain electrode slurry; S3: The electrode slurry obtained in S2 is evenly coated on a conductive carbon cloth, and after vacuum drying, a copper-iron Prussian blue framework material with an ion-confined structure is obtained.

5. The heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field according to claim 4, characterized in that: In step S1, the molar ratio of copper sulfate to potassium ferrocyanide is 1:1; The particle size of the CuFe PBA powder ranges from 10 to 200 nm.

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

1.

7. The heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field according to claim 4, characterized in that: In step S2, the grinding time is 10 to 30 minutes; The total solid content of the electrode slurry is 75-85 wt %.

8. The heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field according to claim 4, characterized in that: In step S3, the coating amount of the electrode slurry is 1-50 mg cm -2 .

9. The method for heavy metal removal based on metal self-corrosion and ion confinement to construct a micro-electric field according to claim 1, characterized in that: In step S3, the vacuum drying temperature is 60-100° C. and the time is 16-20 hours.

10. The heavy metal removal method based on metal self-corrosion and ion confinement to construct a micro-electric field 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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