System and method for simultaneously realizing sewage heavy metal ion adsorption and power generation

Abstract

The present application belongs to the technical field of sewage treatment, and discloses a system and method for realizing sewage heavy metal ion adsorption and power generation simultaneously, wherein a heavy metal ion adsorption cavity and a charge matching cavity are separated by an anion exchange membrane, and spontaneous discharge is realized through the potential difference between the heavy metal ion adsorption electrode and the metal electrode; during the discharge process, the heavy metal ions in the sewage migrate and are adsorbed onto the active material of the heavy metal ion adsorption electrode, and at the same time, the metal electrode releases metal ions into the aqueous solution; after the adsorption is completed, the heavy metal ion adsorption electrode is taken out and is oxidized by using a chemical oxidant to make the heavy metal ions adsorbed by the active material of the electrode to be released, so that the electrode is recycled. The present application has the characteristics of being clean and efficient, and can adsorb various heavy metal ions; more importantly, compared with the traditional heavy metal ion removal process, the system and method do not consume electric energy, but realize energy output, and have a wide application prospect in the field of sewage heavy metal ion treatment.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically, it relates to a system and method for simultaneously achieving the adsorption of heavy metal ions in wastewater and power generation. Background Technology

[0002] Wastewater containing toxic pollutants affects millions of people worldwide and is a major risk factor for disease and death. Among the various pollutants in wastewater, heavy metal ions have attracted widespread attention due to their non-biodegradability, high toxicity, and tendency to accumulate and enrich in organisms through drinking water or the food chain. Therefore, the removal and recovery of heavy metal ions from wastewater is an inherent requirement of the circular economy. To date, various methods have been developed to adsorb heavy metal ions from wastewater, such as chemical precipitation, adsorption, ion exchange, and membrane separation. However, all of these technologies have limitations. For example, chemical precipitation is effective in treating wastewater containing high concentrations of heavy metal ions. However, it is not feasible when the pollution concentration is low. Furthermore, it can cause secondary pollution, requiring further separation. Although physical adsorption has the advantages of simple operation and low cost, problems such as slow adsorption kinetics and limited surface adsorption sites still hinder its development. In addition, the application of ion exchange and membrane separation technologies faces challenges such as membrane regeneration and high costs. Therefore, exploring novel methods with excellent adsorption performance and practical application prospects is of great significance for adsorbing heavy metal ions from wastewater.

[0003] Voltage- or current-driven electrochemical methods are a highly attractive technology for adsorbing heavy metal ions from wastewater. Compared to common physisorption, electrochemical processes offer faster removal kinetics; furthermore, thanks to the adsorption mechanism of redox reactions, their adsorption capacity for heavy metals is generally higher than that of physisorption. Yi Cui and colleagues at Stanford University developed an electrodeposition method for removing heavy metal ions from wastewater. This method can achieve rapid deposition of heavy metals on a conductive substrate under an applied electric field, but it requires a high deposition potential for the heavy metal ions, and the high voltage results in significant energy waste. Electrochemical adsorption separates heavy metal ions from wastewater by adsorbing them onto an active electrode. It has the advantages of low environmental impact and low cost, but it also requires external power, resulting in energy consumption. Therefore, developing a low-energy-consumption electrochemical method for removing heavy metal ions from wastewater is extremely challenging. Summary of the Invention

[0004] This invention aims to solve the technical problems related to the removal of heavy metal ions from wastewater, and provides a system and method for simultaneously achieving the adsorption of heavy metal ions in wastewater and power generation. This method is characterized by being clean and efficient, and can adsorb a variety of heavy metal ions. More importantly, compared with traditional heavy metal ion removal processes, this device does not consume electrical energy, but can instead achieve energy output, and has broad application prospects in the field of wastewater heavy metal ion treatment.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] According to one aspect of the present invention, a system for simultaneously realizing the adsorption of heavy metal ions in wastewater and power generation is provided, characterized in that it includes a heavy metal ion adsorption chamber and a charge matching chamber, the heavy metal ion adsorption chamber and the charge matching chamber being separated by an anion exchange membrane; the heavy metal ion adsorption chamber is provided with a heavy metal ion adsorption electrode and stores wastewater containing heavy metal ions; the charge matching chamber is provided with a metal electrode and stores an aqueous solution containing ions.

[0007] The heavy metal ion adsorption electrode has a positive redox potential, and the metal electrode has a negative redox potential. Through the potential difference between the heavy metal ion adsorption electrode and the metal electrode, spontaneous discharge can be achieved when the heavy metal ion adsorption electrode and the metal electrode are connected to an external resistor.

[0008] During spontaneous discharge, heavy metal ions in the wastewater migrate and are adsorbed onto the active material of the heavy metal ion adsorption electrode under the action of potential difference; at the same time, the metal electrode releases metal ions, and the anion exchange membrane is used to prevent metal ions in the charge matching cavity from migrating to the heavy metal ion adsorption cavity.

[0009] According to another aspect of the present invention, a method for simultaneously achieving heavy metal ion adsorption in wastewater and power generation is provided, comprising a heavy metal ion adsorption chamber and a charge matching chamber, wherein the heavy metal ion adsorption chamber and the charge matching chamber are separated by anion exchange membrane; a heavy metal ion adsorption electrode is disposed in the heavy metal ion adsorption chamber and wastewater containing heavy metal ions is stored therein; a metal electrode is disposed in the charge matching chamber and an aqueous solution containing ions is stored therein.

[0010] The heavy metal ion adsorption electrode has a positive redox potential, and the metal electrode has a negative redox potential. Through the potential difference between the heavy metal ion adsorption electrode and the metal electrode, spontaneous discharge can be achieved when the heavy metal ion adsorption electrode and the metal electrode are connected to an external resistor.

[0011] During spontaneous discharge, heavy metal ions in the wastewater migrate and are adsorbed onto the active material of the heavy metal ion adsorption electrode under the action of potential difference; at the same time, the metal electrode releases metal ions, and the anion exchange membrane is used to prevent metal ions in the charge matching cavity from migrating to the heavy metal ion adsorption cavity.

[0012] In the above systems and methods:

[0013] Furthermore, the active material of the heavy metal ion adsorption electrode has redox activity.

[0014] Preferably, the active material is at least one of a conductive polymer, a metal oxide, or a Prussian blue analogue.

[0015] Furthermore, the metal electrode is made of elemental metal or alloy material.

[0016] Furthermore, the heavy metal ions in the wastewater include at least one of the metal ions with a relative atomic mass greater than 55.

[0017] Furthermore, the ions in the aqueous solution within the charge-matching cavity are one or more of metal ions and non-metal ions.

[0018] Furthermore, after the heavy metal ion adsorption electrode is removed, it is oxidized using a chemical oxidant, which enables the heavy metal ions adsorbed by its active material to be released.

[0019] Furthermore, the chemical oxidant is an oxidizing substance; during the oxidation of the heavy metal ion adsorption electrode, the chemical oxidant itself is reduced.

[0020] Preferably, the chemical oxidant is at least one of oxygen, hydrogen peroxide, and hypochlorite.

[0021] The preparation and use process of the above-mentioned system that simultaneously achieves the adsorption of heavy metal ions in wastewater and power generation is as follows:

[0022] 1) Preparation of heavy metal ion adsorption electrode:

[0023] The active material, conductive agent, and binder are mixed in a certain mass ratio and coated onto a conductive substrate, or they can be directly grown onto a conductive substrate to obtain a heavy metal adsorption electrode.

[0024] In some embodiments, the active material is one or more of conductive polymers, metal oxides, and Prussian blue analogues.

[0025] In some embodiments, the conductive agent is one or more carbon materials such as conductive carbon black, acetylene black, graphene, and carbon nanotubes.

[0026] In some embodiments, the hybrid coating method may also be replaced by vacuum filtration or in-situ growth.

[0027] In some embodiments, the conductive substrate is one of conductive carbon material, aluminum foil, titanium foil, or stainless steel mesh.

[0028] 2) Fabrication of metal electrodes:

[0029] Metal foil can be used directly as an electrode, or metal material can be loaded onto a substrate.

[0030] In some embodiments, the metal foil is one or more of lithium, sodium, potassium, zinc, magnesium, and aluminum.

[0031] In some embodiments, the metallic material is an elemental metal or an alloy.

[0032] In some embodiments, the loading method is one of coating, vapor deposition, or in-situ growth.

[0033] In some embodiments, the substrate is one of conductive carbon material, copper foil, titanium foil, or stainless steel mesh.

[0034] 3) System assembly:

[0035] The system comprises a heavy metal ion adsorption chamber and a charge-matching chamber separated by an anion exchange membrane. In the heavy metal adsorption chamber, wastewater containing heavy metal ions and the heavy metal ion adsorption electrode serve as the electrolyte and electrode, respectively; in the charge-matching chamber, an aqueous solution containing ions and the metal serve as the electrolyte and electrode, respectively.

[0036] Among them, the heavy metal ion adsorption electrode has a positive redox potential, while the metal electrode has a negative redox potential.

[0037] 4) Heavy metal ion adsorption process:

[0038] By utilizing the potential difference between the heavy metal ion adsorption electrode and the metal electrode, spontaneous discharge can be achieved when the heavy metal ion adsorption electrode and the metal electrode are connected to an external resistor.

[0039] During spontaneous discharge, heavy metal ions in wastewater migrate under the influence of potential difference and are adsorbed onto the active material of the heavy metal ion adsorption electrode. At the same time, in order to achieve charge balance of the electrolyte in the device, the metal electrode releases metal ions, and the anion exchange membrane is used to prevent metal ions in the charge matching cavity from migrating to the heavy metal ion adsorption cavity.

[0040] 5) Heavy metal ion desorption process:

[0041] After adsorption is complete, the heavy metal ion adsorption electrode is removed, and the active material is oxidized by a chemical oxidant to remove the heavy metal ions. The heavy metal ion adsorption electrode returns to its initial state, enabling electrode recycling.

[0042] Among them, chemical oxidants are substances with oxidizing properties, such as one or more of oxygen, hydrogen peroxide, and hypochlorite.

[0043] The beneficial effects of this invention are:

[0044] (I) This invention is ingenious in conception, simple in structure and easy to operate. It integrates the dual functions of wastewater heavy metal ion treatment and power generation through a two-electrode structure, effectively solving the problem of energy consumption in the current electrochemical removal of wastewater heavy metal ions.

[0045] (ii) Compared with traditional physical adsorption methods, the present invention has faster kinetics. Traditional physical adsorption takes several days to complete the adsorption of heavy metal ions, while the present invention can complete the adsorption in 1 hour.

[0046] (III) This invention involves a redox reaction on the active material of the heavy metal ion adsorption electrode, resulting in a higher heavy metal ion adsorption capacity compared to physical adsorption methods based on surface physical interactions.

[0047] (iv) The present invention can achieve simultaneous adsorption of multiple heavy metal ions or selective adsorption of a specific heavy metal ion by designing the active material of the heavy metal ion adsorption electrode.

[0048] (iv) The present invention can conveniently desorb heavy metal ions, and the time and voltage of heavy metal ion desorption can also be adjusted according to the requirements. By changing the type of chemical oxidant, the reaction time and the amount added, the desorption time and voltage can be adjusted to meet various actual needs. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the system structure of the present invention that simultaneously achieves the adsorption of heavy metal ions in wastewater and power generation.

[0051] Figure 2 The CuHCF electrode in Example 1 was used in an environment containing 1000 ppm Zn. 2+ Discharge curve in solution.

[0052] Figure 3 The adsorption of Zn in Example 1 2+ The discharge curve of the CuHCF electrode after chemical oxidation.

[0053] Figure 4 The CuHCF electrode in Example 2 was used in an environment containing 1000 ppm Mn. 2+ Discharge curve in solution.

[0054] Figure 5 In Example 2, after Mn adsorption was completed... 2+ The discharge curve of the CuHCF electrode after chemical oxidation.

[0055] Figure 6 The PANI electrode in Example 3 was used in an environment containing 1000 ppm Zn. 2+ Discharge curve in solution.

[0056] Figure 7 The adsorption of Zn in Example 3 2+ The discharge curve of the PANI electrode after chemical oxidation. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0058] The following is a detailed description of the system for simultaneously achieving the adsorption of heavy metal ions in wastewater and power generation according to an embodiment of the present invention.

[0059] like Figure 1 As shown, the following examples use Prussian blue analogue (CuHCF) and conductive polymer (PANI) as active materials for the heavy metal adsorption electrode, zinc foil as the electrode material for the charge matching cavity, and an anion exchange membrane as the diaphragm; the electrolyte for the heavy metal ion adsorption cavity contains heavy metal ions (Zn). 2+ and Mn 2+ The electrolyte in the charge-matching cavity is an aqueous solution containing Na. + The discharge performance in a solution containing heavy metal ions was tested, and the desorption of heavy metal ions was achieved using hydrogen peroxide and oxygen from the air as chemical oxidants.

[0060] In this process, a slurry is formed by uniformly mixing positive electrode active material (Prussian blue analogue and conductive polymer), conductive carbon black and polyvinylidene fluoride in a mass ratio of 7:2:1 using N-methylpyrrolidone (NMP). The slurry is then uniformly coated onto a steel mesh and dried by forced air at 80°C to obtain a heavy metal adsorption electrode.

[0061] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0062] Example 1

[0063] Using CuHCF as the active material for the heavy metal adsorption electrode, zinc foil as the metal electrode for the charge-matching cavity, and an anion exchange membrane as the diaphragm, containing 1000 ppm Zn. 2+ The aqueous solution is the electrolyte in the heavy metal ion adsorption chamber, containing 1000 ppm Na. + The aqueous solution is used as the electrolyte for the charge-matching cavity.

[0064] A constant current discharge test was performed on the system composed of Example 1, and the test results are as follows: Figure 2 and Figure 3 As shown. By Figure 2 The test results show that at a current density of 0.1 A / g, the discharge specific capacity of the adsorption device is 50.1 mAh / g. After the discharge is complete, constant current charging is discontinued until all adsorbed Zn is discharged. 2+ The CuHCF electrode is removed and immersed in an acidic hydrogen peroxide solution, allowing the hydrogen peroxide to come into contact with the discharged CuHCF electrode and undergo a spontaneous redox reaction, thereby completing the desorption process of heavy metal ions. Figure 3 The test results show that the system in Example 1 reached a voltage of 1.72V after self-charging and could be discharged again, with a discharge specific capacity of 46.7mAh / g. This result indicates that during self-charging, the CuHCF electrode is oxidized by hydrogen peroxide. Simultaneously, to maintain charge balance in the system, the zinc metal electrode releases zinc ions, but the anion exchange membrane hinders the migration of zinc ions generated at the negative electrode to the positive electrode side, ultimately reducing the concentration of heavy metal ions in the electrolyte within the heavy metal adsorption chamber.

[0065] Example 2:

[0066] CuHCF is used as the active material for the heavy metal adsorption electrode, zinc foil is used as the metal electrode for the charge-matching cavity, and an anion exchange membrane is used as the diaphragm, containing 1000 ppm Mn. 2+ The aqueous solution is the electrolyte in the heavy metal ion adsorption chamber, containing 1000 ppm Na. + The aqueous solution is used as the electrolyte for the charge-matching cavity.

[0067] A constant current discharge test was performed on the system composed of Example 2, and the test results are as follows: Figure 4 and Figure 5 As shown. By Figure 4 The test results show that at a current density of 0.1 A / g, the discharge specific capacity of the adsorption device is 49.3 mAh / g. After the discharge is complete, constant current charging is discontinued until all Mn adsorbed is removed. 2+ The CuHCF electrode is removed and immersed in an acidic hydrogen peroxide solution, allowing the hydrogen peroxide to come into contact with the discharged CuHCF electrode and undergo a spontaneous redox reaction, thereby completing the desorption process of heavy metal ions. Figure 5 The test results show that the system in Example 1 reached a voltage of 1.68V after self-charging and could be discharged again, with a discharge specific capacity of 48.5mAh / g. This result indicates that during self-charging, the CuHCF electrode is oxidized by hydrogen peroxide. Simultaneously, to maintain charge balance in the system, the zinc metal electrode releases zinc ions, but the anion exchange membrane hinders the migration of zinc ions generated at the negative electrode to the positive electrode side, ultimately reducing the concentration of heavy metal ions in the wastewater adsorption chamber.

[0068] Example 3:

[0069] PANI is used as the active material for the heavy metal adsorption electrode, zinc foil is used as the metal electrode for the charge-matching cavity, and an anion exchange membrane is used as the diaphragm, containing 1000 ppm Zn. 2+ The aqueous solution is the electrolyte in the heavy metal ion adsorption chamber, containing 1000 ppm Na. + The aqueous solution is used as the electrolyte for the charge-matching cavity.

[0070] A constant current discharge test was performed on the system composed of Example 2, and the test results are as follows: Figure 6 and Figure 7 As shown. By Figure 6 The test results show that at a current density of 0.1 A / g, the discharge specific capacity of the adsorption device is 57.7 mAh / g. After the discharge is complete, constant current charging is discontinued until all adsorbed Zn is discharged. 2+ The CuHCF electrode is removed and immersed in an aqueous solution, allowing the dissolved oxygen in the water to come into contact with the PANI electrode after discharge and undergo a spontaneous redox reaction, thereby completing the desorption process of heavy metal ions. Figure 7 The test results show that the system in Example 1 reached a voltage of 1.25V after self-charging and could be discharged again, with a discharge specific capacity of 58.5mAh / g. These results indicate that during self-charging, the PANI electrode is oxidized by oxygen. Simultaneously, to maintain charge balance in the system, the zinc metal electrode releases zinc ions, but the anion exchange membrane hinders the migration of zinc ions generated at the negative electrode to the positive electrode side, ultimately reducing the concentration of heavy metal ions in the wastewater adsorption chamber.

[0071] As can be seen from the above embodiments, the heavy metal ion adsorption system and method proposed in this invention are simple and efficient. Its electrodes can adsorb a variety of heavy metal ions and can be recycled. Most importantly, compared with other electrochemical treatment methods, this invention does not consume energy in the process of adsorbing heavy metal ions in wastewater, but instead outputs electrical energy, which has broad application prospects in the field of wastewater heavy metal ion treatment.

[0072] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A system for simultaneously achieving heavy metal ion adsorption in wastewater and power generation, characterized in that, It includes a heavy metal ion adsorption chamber and a charge matching chamber, which are separated by an anion exchange membrane; the heavy metal ion adsorption chamber is equipped with a heavy metal ion adsorption electrode and stores wastewater containing heavy metal ions; the charge matching chamber is equipped with a metal electrode and stores an aqueous solution containing ions. The active material of the heavy metal ion adsorption electrode has redox activity, and the active material is at least one of conductive polymer, metal oxide, and Prussian blue analogue. The heavy metal ion adsorption electrode has a positive redox potential, and the metal electrode has a negative redox potential. Through the potential difference between the heavy metal ion adsorption electrode and the metal electrode, spontaneous discharge can be achieved when the heavy metal ion adsorption electrode and the metal electrode are connected to an external resistor. During spontaneous discharge, heavy metal ions in the wastewater migrate and are adsorbed onto the active material of the heavy metal ion adsorption electrode under the action of potential difference; at the same time, the metal electrode releases metal ions, and the anion exchange membrane is used to prevent metal ions in the charge matching cavity from migrating to the heavy metal ion adsorption cavity.

2. The system for simultaneously achieving heavy metal ion adsorption and power generation in wastewater according to claim 1, characterized in that, The metal electrode is made of elemental metal or alloy material.

3. The system for simultaneously achieving heavy metal ion adsorption and power generation in wastewater according to claim 1, characterized in that, The heavy metal ions in the wastewater include at least one of the metal ions with a relative atomic mass greater than 55.

4. The system for simultaneously achieving heavy metal ion adsorption and power generation in wastewater according to claim 1, characterized in that, The ions in the aqueous solution within the charge-matching cavity are one or more of metal ions and non-metal ions.

5. The system for simultaneously achieving heavy metal ion adsorption and power generation in wastewater according to claim 1, characterized in that, After the heavy metal ion adsorption electrode is removed from the adsorption process, it is oxidized with a chemical oxidant to remove the heavy metal ions adsorbed by the active material.

6. A system for simultaneously achieving heavy metal ion adsorption and power generation in wastewater according to claim 5, characterized in that, The chemical oxidant is a substance with oxidizing properties; during the oxidation of the heavy metal ion adsorption electrode, the chemical oxidant itself is reduced.

7. A system for simultaneously achieving heavy metal ion adsorption and power generation in wastewater according to claim 6, characterized in that, The chemical oxidant is at least one of oxygen, hydrogen peroxide, and hypochlorite.

8. A method for simultaneously achieving heavy metal ion adsorption and power generation in wastewater, characterized in that, The system includes a heavy metal ion adsorption chamber and a charge matching chamber, which are separated by an anion exchange membrane. The heavy metal ion adsorption chamber contains a heavy metal ion adsorption electrode and stores wastewater containing heavy metal ions. The charge matching chamber contains a metal electrode and stores an aqueous solution containing ions. The active material of the heavy metal ion adsorption electrode has redox activity, and the active material is at least one of conductive polymer, metal oxide, and Prussian blue analogue. The heavy metal ion adsorption electrode has a positive redox potential, and the metal electrode has a negative redox potential. Due to the potential difference between the heavy metal ion adsorption electrode and the metal electrode, spontaneous discharge can be achieved when the heavy metal ion adsorption electrode and the metal electrode are connected to an external resistor. During spontaneous discharge, heavy metal ions in the wastewater migrate and are adsorbed onto the active material of the heavy metal ion adsorption electrode under the action of potential difference; at the same time, the metal electrode releases metal ions, and the anion exchange membrane can prevent metal ions in the charge matching cavity from migrating to the heavy metal ion adsorption cavity.

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