A microbial fuel cell particle for removing heavy metal pollutants from water bodies and a preparation method thereof

Abstract

The present application relates to the field of ecological environmental protection, and particularly relates to a microbial fuel cell particle for removing heavy metal pollutants in water and a preparation method thereof. The microbial fuel cell particle comprises an electricity-producing bacteria substrate, a gel layer, an anode and a cathode. The electricity-producing bacteria substrate, the gel layer and the cathode are sequentially wrapped outside the anode, and the anode and the cathode are connected by a wire. The electricity-producing bacteria substrate is a mixture of activated sludge or wetland sediment and straw powder, wherein the activated sludge or wetland sediment contains a large number of electricity-producing bacteria, and the straw powder provides a carbon source for the electricity-producing bacteria. When the water is polluted by heavy metals, the microbial fuel cell particle can be put into the water. The electrons generated by the electricity-producing bacteria reach the cathode through the anode and the wire. These electrons reduce and adsorb the heavy metal ions in the water on the surface of the cathode, thereby achieving water remediation. The microbial fuel cell particle does not contain harmful chemicals, and the remediation process does not produce secondary pollution. After the remediation is completed, the particle can be salvaged out of the water, the cathode can be disassembled, and the heavy metals can be recovered by elution.

Description

Technical Field

[0001] This invention relates to the field of ecological and environmental protection technology, specifically to a microbial fuel cell particle for removing heavy metal pollutants from water and its preparation method. Background Technology

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

[0003] Currently, 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 suffer from high costs and energy consumption, requiring large amounts of chemical reagents or energy. Furthermore, some methods may trigger new environmental pollution problems, leading to secondary pollution (Zhang Zuye et al., Acta Microbiologica Sinica, 2023, 63(7): 2791-2808). Therefore, developing green and sustainable heavy metal pollution control technologies has become an important direction for current environmental science research.

[0004] Microbial fuel cells (MFCs) generate electrons by decomposing organic matter through electrogenic microorganisms. These electrons are then transferred to the anode via extracellular electron transport. The electrons are subsequently transported to the cathode via wires, where they undergo a reduction reaction with oxidizing substances such as dissolved oxygen in the water. Based on this principle, MFCs, as an innovative treatment technology, can achieve highly efficient reduction and removal of heavy metals such as Cu(II) and Cr(VI) in the cathode region. The operation requires no external energy input and is characterized by being 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, when removing heavy metals from water, the wastewater must be placed in the cathode chamber for removal on the cathode surface. Constrained by cost and remediation effectiveness, large-volume MFCs lack practical application value; therefore, traditional two-chamber MFC structures are difficult to apply to water remediation under field conditions.

[0005] Therefore, there is a need to design a new type of MFC device and method that can retain the principle of MFC in removing heavy metals, but also overcome the limitations of the dual-chamber structure and cost of MFC, for in-situ remediation of water bodies contaminated with heavy metals. Summary of the Invention

[0006] The purpose of this invention is to provide microbial fuel cell particles that remove heavy metal contaminants from water, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides microbial fuel cell particles for removing heavy metal pollutants from water, comprising: an anode, an electrogenic bacterial matrix, a gel layer, and a cathode; the anode is encapsulated in the electrogenic bacterial matrix, the electrogenic bacterial matrix is ​​encapsulated in the gel layer, the gel layer is encapsulated in 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 porous conductive material filling the space between them.

[0009] Furthermore, the conductive carbon material in the anode material includes graphite felt, graphene, carbon felt, carbon cloth, and carbon brush.

[0010] Furthermore, the electrogenic bacteria substrate is a mixture of activated sludge or wetland sediment and straw powder.

[0011] Furthermore, the gel layer is agar or trehalose gel.

[0012] The present invention also provides a method for preparing microbial fuel cell particles for removing heavy metal pollutants from water as described above, comprising the following steps:

[0013] Step 1: Mix straw powder into activated sludge or wetland sediment to obtain an electrogenic bacteria substrate, and wrap the anode in it to form spherical particles to obtain an electrogenic bacteria substrate containing the anode.

[0014] Step 2: After melting the agar or trehalose gel, cool it to 40-50°C. Immerse the electrogenic bacteria matrix containing the anode prepared in Step 1 in the agar or trehalose gel and quickly lift it out. After the surface cools, a gel layer is formed.

[0015] Step 3: The spherical particles encapsulating the gel layer are sealed in a hollow sphere made of two layers of stainless steel mesh. The space between the two layers of stainless steel mesh is filled with a porous conductive material to form the cathode. The porous conductive material includes carbon felt, graphite felt, activated carbon, and foamed titanium. The anode and cathode are connected with titanium wire to complete the preparation of microbial fuel cell particles.

[0016] Further, in step 1, the mass percentage of straw powder to activated sludge or wetland sediment is 0%-50%, preferably 2%-10%.

[0017] Furthermore, in step 3, the aperture of the stainless steel mesh is ≤100 mesh, which can be adjusted according to different porous conductive materials, as long as it does not leak.

[0018] This invention also provides an application of the microbial fuel cell particles prepared by the method described above in the removal of heavy metal pollutants from water. When water bodies are contaminated with heavy metals, a large number of microbial fuel cell particles are introduced into the water. Electrons generated by the electrogenic bacteria in the wetland sediment or activated sludge inside the particles from the decomposition of straw powder pass sequentially through the anode and wires to the cathode surface. These electrons can reduce and adsorb heavy metal ions in the water onto the cathode surface, reducing the heavy metal content in the water and achieving water remediation. After the remediation is completed, the particles are retrieved from the water, and the cathode is disassembled and washed to recover the heavy metals, thus allowing the cathode to be reused.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The microbial fuel cell particles of this invention break through the limitations of the traditional dual-chamber MFC configuration. Sufficient MFC particles can be added and submerged in water to remove heavy metals, depending on the degree of water pollution. In principle, electrogenic substrates such as activated sludge and wetland sediment contain a large number of electrogenic bacteria, and straw powder, as a carbon source, can promote the growth of these bacteria and increase electricity production. Electrogenic bacteria on the anode surface transfer the generated electrons to the anode, which then travel through wires to the cathode surface. This not only creates an electric field at the cathode to adsorb heavy metal ions but also reduces the heavy metals to lower valence states or elemental forms, thereby reducing toxicity and depositing them on the cathode surface. This prevents the heavy metal ions from being released back into the water. Furthermore, heavy metals can be recovered by retrieving the microbial fuel cell particles, turning waste into treasure. In addition, the microbial fuel cell particles do not contain any harmful chemicals, and the remediation process does not generate secondary pollution. Attached Figure Description

[0021] Figure 1 The curves showing the change in Cu concentration over 48 hours for the addition of microbial fuel cell particles and the control in Example 1;

[0022] Figure 2 XPS analysis results of the microbial fuel cell particulate cathode carbon felt mixed with 2% straw powder in Example 1;

[0023] Figure 3 The curves showing the Cr concentration changes over 48 hours for the addition of microbial fuel cell particles and the control in Example 2;

[0024] Figure 4 A schematic diagram of the structure of microbial fuel cell particles used to remove heavy metal pollutants from water.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1 is the anode, 2 is the electrogenic bacterial substrate, 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; among them, the inner stainless steel mesh 4, the porous conductive material 5, and the outer stainless steel mesh 6 together form the cathode. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention relates to microbial fuel cell particles for removing heavy metal contaminants from water, such as... Figure 4 As shown, it includes: an anode 1, an electrogenic bacterial matrix 2, a gel layer 3, and a cathode; the anode 1 is wrapped in the electrogenic bacterial matrix 2, the electrogenic bacterial matrix 2 is wrapped in the gel layer 3, the gel layer 3 is wrapped in the cathode, and the anode 1 and the cathode are connected by a wire.

[0029] The anode 1 is made of stainless steel, titanium, or conductive carbon material.

[0030] The cathode consists of two layers of stainless steel mesh (inner stainless steel mesh 4 and outer stainless steel mesh 6) with porous conductive material 5 filling the space between them. 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.

[0031] The electrogenic bacteria substrate 2 is a mixture of activated sludge or wetland sediment and straw powder, wherein 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%.

[0032] The third gel layer is an agar or trehalose gel. Example 1

[0033] The preparation of microbial fuel cell particles includes the following steps:

[0034] (1) 0%, 2% and 10% straw powder were mixed into the activated sludge as substrate for electrogenic bacteria. After wrapping the carbon felt in it, 6 spherical particles with a diameter of 6 cm were made. Each straw powder content was used to make two spherical particles.

[0035] (2) After melting the agar, cool it to 43°C, immerse the prepared spherical particles in the agar and quickly lift them out. After the surface cools, an agar layer is formed.

[0036] (3) The spherical particles coated with agar were enclosed in a hollow sphere made of two layers of 10-mesh stainless steel mesh, with a 3 mm gap between the two layers of stainless steel. Carbon felt was then used to fill the sphere to form the cathode. The anode and cathode were connected with titanium wire to complete the preparation of microbial fuel cell particles.

[0037] 1L of Cu was added to each of five 2L beakers. 2+ Concentration 100 mg / L -1 A CuCl2 solution was prepared. Three beakers were used, each containing two microbial fuel cell particles with the same straw powder content. Two other beakers were prepared as follows: one without microbial fuel cell particles (control A), and the other containing two microbial fuel cell particles without leads (control B). The preparation of the microbial fuel cell particles without leads was the same as that of the microbial fuel cell particles with 2% straw content, except the leads 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 Cu content was determined using a flame atomic absorption spectrometer. 2+ concentration. Figure 1 The results showed that within 48 hours of adding microbial fuel cell particles to a CuCl2 solution, the Cu in the solution decreased... 2+ The concentration of Cu in the solutions treated with 0%, 2%, and 10% straw powder particles decreased continuously at 48 hours. 2+ The concentrations were reduced to only 22.97 mg / L. -1 8.01 mg / L -1 3.85 mg / L -1 While Cu from 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 and subjected to X-ray photoelectron spectroscopy (XPS) analysis, such as... Figure 2 As shown, reduced copper (elemental Cu and Cu) exists on the cathode surface at 932.70 eV and 952.75 eV. + Characteristic peaks of Cu are observed at 934.85 eV and 954.55 eV. 2+ Characteristic peaks.

[0038] Example 1 shows that adding microbial fuel cell particles can significantly reduce Cu in the solution. 2+ Concentration, which helps to restore water quality; and increasing the proportion of straw powder can enhance the effect on Cu 2+ XPS analysis showed that the microbial fuel cell particles effectively removed Cu from the water. 2+ The mechanism is the adsorption of Cu 2+ and part of Cu 2+Reduced to elemental Cu and Cu + In control B, without the wires installed, the electrons produced by the electrogenic bacteria cannot reach the cathode surface, thus the cathode cannot form an electric field to adsorb Cu. 2+ It also cannot provide electronic reduction of Cu 2+ Only by adsorbing a small amount of Cu on the carbon felt itself 2+ Thus, Cu in the solution 2+ The concentration decreased by only about 5%. Example 2

[0039] The preparation of microbial fuel cell particles includes the following steps:

[0040] (1) 0%, 5% and 10% straw powder were mixed into the activated sludge as substrates for electrogenic bacteria. After wrapping the carbon felt in the substrates, six spherical particles with a diameter of 15 cm were made. Each straw powder content was used to make two spherical particles.

[0041] (2) After melting the agar, cool it to 46°C, immerse the prepared spherical particles in the agar and quickly lift them out. After the surface cools, an agar layer is formed.

[0042] (3) The spherical particles coated with agar were sealed in a hollow sphere made of two layers of 60-mesh stainless steel mesh with a 5 mm gap between the two layers of stainless steel mesh, and graphite felt was filled in to form the cathode. The anode and cathode were connected with titanium wire to complete the preparation of microbial fuel cell particles.

[0043] 15L of Cr was poured into each of five 20L PE containers. 6+ Concentration 100 mg / L -1 K₂CrO₄ solution was prepared. Three containers were used, each containing two microbial fuel cell particles with the same straw powder content. The other two containers were used in two ways: one without microbial fuel cell particles (control A), and the other containing the same mass of graphite felt as the two microbial fuel cell particles (control B). After 1, 12, 24, 36, and 48 hours, 0.5 mL of K₂CrO₄ solution was taken and the Cr content was determined using flame atomic absorption spectrometry. 6+ concentration. Figure 3 The results showed that within 48 hours of adding microbial fuel cell particles to a K₂CrO₄ solution, the Cr content in the solution decreased. 6+ The concentration continuously decreased. At the 48th hour, the Cr content of the solutions treated with 0%, 5%, and 10% straw powder particles was... 6+ The concentration was only 33.36 mg / L. -1 15.7 mg / L -1 15.22 mg / L -1 While the Cr of control A and control B 6+ The concentrations were 99.06 mg / L.-1 and 94.21 mgL -1 .

[0044] Example 2 shows that adding microbial fuel cell particles can significantly reduce Cr in the solution. 6+ Concentration, to achieve the effect of water body restoration; while increasing the proportion of straw powder can enhance the effect of Cr. 6+ The removal effect was observed. Control B only added graphite felt as the cathode material; due to the lack of electrons generated by electrogenic bacteria, the graphite felt could not form an electric field to adsorb Cr. 6+ It also cannot provide electronic reduction of Cr 6+ The graphite felt itself only adsorbs a small amount of Cr 6+ Thus, the Cr in the solution 6+ The concentration decreased by only about 6%.

[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0046] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. The application of microbial fuel cell particles in the removal of heavy metal pollutants from water, characterized in that, The microbial fuel cell particles for removing heavy metal pollutants from water include: an anode (1), an electrogenic bacterial matrix (2), a gel layer (3), and a cathode; the anode (1) is wrapped in the electrogenic bacterial matrix (2), the electrogenic bacterial matrix (2) is wrapped in the gel layer (3), the gel layer (3) is wrapped in the cathode, and the anode (1) and the cathode are connected by a wire; The electrogenic microbial substrate (2) is a mixture of activated sludge or wetland sediment and straw powder; the mass percentage of the straw powder to activated sludge or wetland sediment is 2%-5%; The gel layer (3) is agar or trehalose gel; 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 between. The porous conductive material (5) is selected from carbon felt, graphite felt, activated carbon, and foamed titanium.

2. The application of microbial fuel cell particles according to claim 1 in the removal of heavy metal pollutants from water, characterized in that, The anode (1) is made of stainless steel, titanium or conductive carbon material.

3. The application of microbial fuel cell particles according to claim 1 in the removal of heavy metal pollutants from water, characterized in that, The method for preparing the microbial fuel cell particles for removing heavy metal contaminants from water includes the following steps: Step 1: Mix straw powder into activated sludge or wetland sediment to obtain electrogenic bacteria substrate (2), and wrap the anode (1) in it to form spherical particles to obtain electrogenic bacteria substrate (2) containing the anode. Step 2: After melting the agar or trehalose gel, cool it to 40-50°C. Immerse the electrogenic bacteria substrate (2) containing the anode prepared in Step 1 in the agar or trehalose gel and quickly lift it out. After the surface cools, a gel layer (3) is formed. Step 3: The spherical particles encapsulating the gel layer (3) are sealed in a hollow sphere made of two layers of stainless steel mesh, and the space between the two layers of stainless steel mesh is filled with porous conductive material to form a cathode; the anode and cathode are connected with titanium wire to complete the preparation of microbial fuel cell particles; In step 1, the mass percentage of straw powder to activated sludge or wetland sediment is 2%-5%.

4. The application of microbial fuel cell particles according to claim 3 in the removal of heavy metal pollutants from water, characterized in that, In step 3, the aperture of the stainless steel mesh is ≤100 mesh.

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