Microbial fuel cell particles for removing heavy metal pollutants in water body and preparation method of microbial fuel cell particles

Abstract

The invention relates to the technical field of ecological environmental protection, in particular to microbial fuel cell particles for removing heavy metal pollutants in a water body and a preparation method of the microbial fuel cell particles. The anode is sequentially wrapped with an electrogenesis bacterium matrix, a gel layer and a cathode, and the anode and the cathode are connected through a wire; the electrogenesis bacterium substrate is a mixture of activated sludge or wetland bottom mud and straw powder, the activated sludge or the wetland bottom mud contains a large amount of electrogenesis bacteria, and the straw powder provides a carbon source for the electrogenesis bacteria; when the water body is polluted by heavy metals, the microbial fuel cell particles can be put into the water, electrons generated by the current-producing bacteria reach the cathode through the anode and the wire, and heavy metal ions in the water are reduced and adsorbed on the surface of the cathode by the electrons, so that the water body is repaired; the microbial fuel cell particles do not contain harmful chemical substances, and secondary pollution is not generated in the repairing process; after repairing is finished, the particles can be fished out of water, and heavy metal is recovered through elution after the cathode is detached.

Description

Technical Field

[0001] The present invention relates to the field of ecological environmental protection technology, and in particular to microbial fuel cell particles for removing heavy metal pollutants from water bodies and a preparation method thereof. Background Art

[0002] With the acceleration of industrialization, heavy metal pollution is becoming increasingly serious. Industrial wastewater, particularly from electroplating, mining, and electronics manufacturing, is a major source of heavy metal pollution. These wastewaters contain large amounts of heavy metal ions, such as copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn). These ions are non-biodegradable, environmentally persistent, and highly toxic. Their accumulation in water bodies can have toxic effects on aquatic organisms and accumulate through the food chain, ultimately endangering human life and health.

[0003] Currently, the remediation technologies for heavy metal-contaminated water bodies mainly include physical adsorption, electrochemical separation, ion exchange, filtration, chemical precipitation, and solvent extraction. However, these technologies generally have the problems of high cost and high energy consumption, and require the consumption of large amounts of chemical reagents or energy. In addition, some methods may cause new environmental pollution problems and lead to the occurrence of secondary pollution (Zhang Zuye et al. Acta Microbiologica Sinica, 2023, 63(7): 2791-2808). Therefore, the development of green and sustainable heavy metal pollution control technologies has become an important direction of current environmental science research.

[0004] Microbial fuel cells (MFCs) generate electrons through the decomposition of organic matter by electrogenic microorganisms. These electrons are then transferred to the anode via an extracellular electron transfer mechanism. The electrons are then transported via wires to the cathode, where they undergo a reduction reaction with oxidizing substances such as dissolved oxygen in the water. Based on this principle, MFCs, as an innovative remediation technology, can achieve efficient reduction and removal of heavy metals such as Cu(II) and Cr(VI) in the cathode region. The operation process requires no external energy input, making them clean, safe, sustainable, and easy to operate. However, MFCs typically consist of an anode chamber, a cathode chamber, and a cation exchange membrane, resulting in high costs. Furthermore, to remove heavy metals from water bodies, wastewater must be placed in the cathode chamber for removal on the cathode surface. Due to cost constraints and remediation effectiveness, large-volume MFCs lack practical application, making traditional dual-chamber MFCs difficult to apply for water remediation in the field.

[0005] Therefore, it is necessary to design a new MFC device and method that can retain the principle of MFC for removing heavy metals but break through the dual-chamber structure and cost limitations of MFC for in situ remediation of heavy metal-contaminated water bodies. Summary of the Invention

[0006] The purpose of the present invention is to provide a microbial fuel cell particle for removing heavy metal pollutants in water bodies, so as to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a microbial fuel cell particle for removing heavy metal pollutants in water bodies, comprising: an anode, an electrogenic bacteria matrix, a gel layer and a cathode; the anode is wrapped in the electrogenic bacteria matrix, the electrogenic bacteria matrix is ​​wrapped in the gel layer, the gel layer is wrapped by the cathode, and the anode and cathode are connected by a wire; the anode is made of stainless steel, titanium or conductive carbon material; the cathode is composed of two layers of stainless steel mesh (inner stainless steel mesh and outer stainless steel mesh) with a porous conductive material filled in the middle.

[0008] Furthermore, the conductive carbon material in the anode material includes graphite felt, graphene, carbon felt, carbon cloth, and carbon brush.

[0009] Furthermore, the electrogenic bacteria matrix is ​​a mixture of activated sludge or wetland sediment and straw powder.

[0010] Furthermore, the gel layer is agar or trehalose gel.

[0011] The present invention also provides a method for preparing microbial fuel cell particles for removing heavy metal pollutants from water bodies as described above, comprising the following steps: Step 1: mixing straw powder into activated sludge or wetland sediment to obtain an electrogenic bacteria matrix, and wrapping the anode in the matrix to form spherical particles to obtain an electrogenic bacteria matrix containing the anode; Step 2: Melt the agar or trehalose gel and cool it to 40-50° C. Then, immerse the electrogenic bacteria matrix containing the anode prepared in step 1 in the agar or trehalose gel and quickly remove it. After the surface cools, a gel layer is formed. In step 3, the spherical particles wrapped with the gel layer are enclosed in a hollow sphere made of two layers of stainless steel mesh. A porous conductive material is filled between the two layers of stainless steel mesh to form a cathode. The porous conductive material includes carbon felt, graphite felt, activated carbon, and titanium foam. The anode and cathode are connected with titanium wire to complete the preparation of microbial fuel cell particles.

[0012] Furthermore, in step 1, the mass percentage of straw powder to activated sludge or wetland sediment is 0%-50%, and preferably the mass percentage of straw powder to activated sludge or wetland sediment is 2%-10%.

[0013] Furthermore, in step 3, the pore size of the stainless steel mesh is ≤100 mesh, and can be adjusted according to different porous conductive materials as long as there is no leakage.

[0014] The present invention also provides a method for using the microbial fuel cell particles prepared using the above-described preparation method to remove heavy metal contaminants from water bodies. When heavy metal contamination occurs in a water body, a large number of microbial fuel cell particles are added to the water. Electrons generated by the decomposition of straw powder by electrogenic bacteria in wetland sediment or activated sludge within the particles pass through the anode and wires to the cathode surface. These electrons can reduce heavy metal ions in the water and adsorb them on the cathode surface, reducing the heavy metal content in the water and achieving water remediation. After remediation is completed, the particles are salvaged from the water, and the cathode is disassembled and the heavy metals are recovered through elution, making the cathode reusable.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The microbial fuel cell particles of the present invention break through the limitations of the traditional MFC dual-chamber configuration. According to the degree of water pollution, sufficient MFC particles can be added to sink into the water to remove heavy metals. In principle, activated sludge and wetland sediment, etc., contain a large number of electrogenic bacteria in the electrogenic bacteria matrix, and straw powder as a carbon source can promote the growth of electrogenic bacteria and increase electricity production. The electrogenic bacteria on the anode surface transfer the generated electrons to the anode. After reaching the cathode surface through the wire, not only an electric field is formed at the cathode to adsorb heavy metal ions, but also heavy metals are reduced to low-valent states or elements, thereby reducing toxicity and plating on the cathode surface, avoiding the re-release of heavy metal ions back into the water. At the same time, heavy metal recovery can be achieved by salvaging the microbial fuel cell particles, turning waste into treasure. In addition, the microbial fuel cell particles do not contain any harmful chemicals, and the repair process does not produce secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Cu concentration change curves of the microbial fuel cell particles added in Example 1 and the control within 48 hours; Figure 2 XPS analysis results of the microbial fuel cell granular cathode carbon felt mixed with 2% straw powder in Example 1; Figure 3 The Cr concentration change curve of the microbial fuel cell particles added in Example 2 and the control within 48 hours; Figure 4 Schematic diagram of the structure of microbial fuel cell particles for removing heavy metal pollutants from water.

[0017] Description of reference numerals: 1 is the anode, 2 is the electrogenic bacteria matrix, 3 is the gel layer, 4 is the inner stainless steel mesh, 5 is the porous conductive material, 6 is the outer stainless steel mesh, and 7 is the wire; the inner stainless steel mesh 4, the porous conductive material 5, and the outer stainless steel mesh 6 together constitute the cathode. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] The present invention provides a microbial fuel cell particle for removing heavy metal pollutants from water bodies. Figure 4 As shown, it includes: an anode 1, an electrogenic bacteria matrix 2, a gel layer 3 and a cathode; the anode 1 is wrapped in the electrogenic bacteria matrix 2, the electrogenic bacteria matrix 2 is wrapped in the gel layer 3, the gel layer 3 is wrapped by the cathode, and the anode 1 and the cathode are connected by a wire.

[0020] The material of the anode 1 is stainless steel, titanium or conductive carbon material.

[0021] The cathode is composed of two layers of stainless steel mesh (inner stainless steel mesh 4, outer stainless steel mesh 6) with porous conductive material 5 filled in the middle. The porous conductive material includes carbon felt, graphite felt, activated carbon, and foamed titanium. The pore size of the stainless steel mesh is ≤100 mesh and can be adjusted according to different porous conductive materials as long as there is no leakage.

[0022] The electrogenic bacteria substrate 2 is a mixture of activated sludge or wetland sediment and straw powder, the mass percentage of straw powder to activated sludge or wetland sediment is 0%-50%, and the preferred mass percentage of straw powder to activated sludge or wetland sediment is 2%-10%.

[0023] The gel layer 3 is agar or trehalose gel. Example 1

[0024] The preparation of microbial fuel cell particles includes the following steps: (1) 0%, 2%, and 10% straw powder were mixed into the activated sludge as the substrate for electrogenic bacteria, and carbon felt was wrapped in it to make six spherical particles with a diameter of 6 cm, of which two spherical particles were made for each straw powder content; (2) Melt the agar and cool it to 43°C. Immerse the prepared spherical particles in the agar and quickly pick them up. After the surface cools, an agar layer is formed. (3) The spherical particles wrapped in the agar layer were enclosed in a hollow sphere made of two layers of 10-mesh stainless steel mesh, with a distance of 3 mm between the two layers of stainless steel. Carbon felt was filled to form the cathode. The anode and cathode were connected with titanium wire to complete the preparation of the microbial fuel cell particles.

[0025] 1L of Cu was placed in each of the five 2L beakers. 2+ Concentration 100 mg / L -1CuCl2 solution. In each of the three beakers, two microbial fuel cell particles with the same straw powder content were added. In the other two beakers, one was not added with microbial fuel cell particles as control A, and the remaining beaker was added with two microbial fuel cell particles without wires as control B. The preparation of the microbial fuel cell particles without wires was the same as the microbial fuel cell particles with a straw content of 2%, except that the wires were removed. After 1, 12, 24, 36, and 48 hours, 0.5 mL of CuCl2 solution was taken from each of the five beakers and the CuCl2 content was determined by flame atomic absorption spectrometry. 2+ concentration. Figure 1 It shows that within 48 hours of adding microbial fuel cell particles to CuCl2 solution, the Cu 2+ The concentration decreased continuously, and the Cu content of the solution treated with 0%, 2%, and 10% straw powder particles at 48 hours was 2+ The concentrations were only 22.97 mg / L -1 , 8.01 mgL -1 , 3.85 mgL -1 , while the Cu of control A and control B 2+ The concentrations were 98.91 mg / L -1 and 94.62 mgL -1 The microbial fuel cell granular cathode carbon felt mixed with 2% straw powder was taken out for X-ray photoelectron spectroscopy (XPS) analysis. Figure 2 As shown, there is reduced copper (elemental Cu and Cu) on the cathode surface at 932.70 eV and 952.75 eV. + ) characteristic peaks; Cu 2+ characteristic peaks.

[0026] Example 1 shows that adding microbial fuel cell particles can significantly reduce the Cu 2+ concentration, which has the effect of repairing water bodies; and increasing the proportion of straw powder can increase the 2+ XPS analysis shows that the microbial fuel cell particles can remove Cu 2+ The mechanism is the adsorption of Cu 2+ and part of Cu 2+ Reduced to elemental Cu and Cu + In control B, no wires were installed, and the electrons produced by the electrogenic bacteria could not reach the cathode surface, so the cathode could not form an electric field to adsorb Cu 2+ , and cannot provide electrons to reduce Cu 2+ , relying solely on the carbon felt itself to adsorb a small amount of Cu 2+ , so that Cu in solution 2+ The concentration decreased by only about 5%. Example 2

[0027] The preparation of microbial fuel cell particles includes the following steps: (1) 0%, 5%, and 10% straw powder were mixed into activated sludge as the substrate for electrogenic bacteria, and carbon felt was wrapped in it to make six spherical particles with a diameter of 15 cm, of which two spherical particles were made for each straw powder content.

[0028] (2) Melt the agar and cool it to 46°C. Immerse the prepared spherical particles in the agar and quickly pick them up. After the surface cools, an agar layer is formed. (3) The spherical particles wrapped in the agar layer were enclosed in a hollow sphere made of two layers of 60-mesh stainless steel mesh, with a distance of 5 mm between the two layers of stainless steel. Graphite felt was filled in to form the cathode. The anode and cathode were connected with titanium wire to complete the preparation of the microbial fuel cell particles.

[0029] 15L of Cr was placed in each of 5 20L PE barrels. 6+ Concentration 100 mg / L -1 Of the three barrels, two microbial fuel cell pellets with the same straw powder content were added to each barrel. In the other two barrels, one was not added with microbial fuel cell pellets as control A, and the remaining one was added with the same mass of graphite felt as the two microbial fuel cell pellets as control B. After 1, 12, 24, 36, and 48 hours, 0.5 mL of K2CrO4 solution was taken from each beaker and Cr was measured using a flame atomic absorption spectrometer. 6+ concentration. Figure 3 It shows that within 48 hours of adding microbial fuel cell particles to K2CrO4 solution, the Cr content in the solution 6+ The concentration continued to decrease. At 48 hours, the Cr content of the solution treated with 0%, 5%, and 10% straw powder particles 6+ The concentrations were only 33.36 mg / L -1 , 15.7 mgL -1 , 15.22 mgL -1 , while the Cr of control A and control B 6+ The concentrations were 99.06 mg / L -1 and 94.21 mgL -1 .

[0030] Example 2 shows that adding microbial fuel cell particles can significantly reduce the Cr content in the solution. 6+ concentration, which has the effect of repairing water bodies; and increasing the proportion of straw powder can increase the 6+ The control B only added the cathode material graphite felt, but due to the lack of electrons produced by the electrogenic bacteria, the graphite felt could not form an electric field to adsorb Cr.6+ , and cannot provide electrons to reduce Cr 6+ , relying solely on the graphite felt itself to absorb a small amount of Cr 6+ , so that Cr in the solution 6+ The concentration decreased by only about 6%.

[0031] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0032] It should be noted that the above content merely illustrates the technical idea of ​​the present invention and cannot be used to limit the scope of protection of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications all fall within the scope of protection of the claims of the present invention.

Claims

1. A microbial fuel cell particle for removing heavy metal pollutants from water bodies, characterized in that: include: An anode (1), an electrogenic bacteria matrix (2), a gel layer (3) and a cathode; the anode (1) is wrapped in the electrogenic bacteria matrix (2), the electrogenic bacteria matrix (2) is wrapped in the gel layer (3), the gel layer (3) is wrapped by the cathode, and the anode (1) and the cathode are connected by a wire.

2. The microbial fuel cell particle for removing heavy metal pollutants from water bodies according to claim 1, characterized in that: The anode (1) is made of stainless steel, titanium or conductive carbon material.

3. The microbial fuel cell particle for removing heavy metal pollutants from water bodies according to claim 1, characterized in that: The cathode is composed of an inner stainless steel mesh (4), an outer stainless steel mesh (6), and a porous conductive material (5) filled in the middle. The porous conductive material (5) includes carbon felt, graphite felt, activated carbon, and foamed titanium.

4. The microbial fuel cell particle for removing heavy metal pollutants from water bodies according to claim 1, characterized in that: The electrogenic bacteria matrix (2) is a mixture of activated sludge or wetland sludge and straw powder.

5. The microbial fuel cell particle for removing heavy metal pollutants from water bodies according to claim 1, characterized in that: The gel layer (3) is agar or trehalose gel.

6. A method for preparing microbial fuel cell particles for removing heavy metal pollutants from water bodies according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: mixing straw powder into activated sludge or wetland sediment to obtain an electrogenic bacteria matrix (2), encapsulating the anode (1) therein to form spherical particles, and obtaining an electrogenic bacteria matrix (2) containing the anode; Step 2: melt the agar or trehalose gel and cool it to 40-50°C. Then, immerse the electrogenic bacteria matrix (2) containing the anode prepared in step 1 in the agar or trehalose gel and quickly remove it. After the surface cools, a gel layer (3) is formed. Step 3, enclosing the spherical particles wrapped with the gel layer (3) in a hollow sphere made of two layers of stainless steel mesh, filling the space between the two layers of stainless steel mesh with a porous conductive material to form a cathode; connecting the anode and cathode with titanium wire to complete the preparation of microbial fuel cell particles.

7. The method for preparing microbial fuel cell particles for removing heavy metal pollutants from water bodies according to claim 6, characterized in that: In step 1, the mass percentage of straw powder to activated sludge or wetland sediment is 0%-50%.

8. The method for preparing microbial fuel cell particles for removing heavy metal pollutants from water bodies according to claim 6, characterized in that: In step 3, the pore size of the stainless steel mesh is ≤100 mesh.

9. Use of the microbial fuel cell particles prepared by the preparation method according to any one of claims 6 to 8 in removing heavy metal pollutants from water bodies.

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