A pollutant degradation material based on a mineral-microorganism interface capacitance effect and a preparation method and application thereof

Abstract

The application provides a pollutant degradation material based on a mineral-microorganism interface capacitance effect and a preparation method and application thereof, and belongs to the field of environmental functional materials and microbial photochemistry cross technology. The pollutant degradation material is composed of a semiconductor iron mineral and an electroactive microorganism, and a heterojunction structure with a capacitance characteristic is formed at the interface. The preparation method of the application is to oscillate and co-culture the sterilized semiconductor iron mineral and the electroactive microorganism in a PBS buffer solution under anaerobic conditions, so as to construct an electron storage and release channel at the interface. The equivalent circuit of the degradation material is a double-time constant model, which significantly reduces the charge transfer resistance. The degradation rate of the material to tetracycline hydrochloride under 120 min illumination is more than 84%, and the degradation activity is still excellent under anaerobic conditions, which provides an efficient, stable and novel solution for green remediation of environmental pollution.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of environmental functional materials and microbial photochemistry, specifically relating to a pollutant degradation material based on the mineral-microbial interface capacitance effect, its preparation method, and its application. Background Technology

[0002] In recent years, the problem of antibiotic residues and accumulation in the environment has become increasingly prominent, especially tetracycline antibiotics, whose persistent presence in soil and water poses a serious threat to ecosystems and public health. Currently used treatment technologies include physical adsorption, chemical oxidation, and biodegradation, but they generally face problems such as low degradation efficiency, high treatment costs, and easy secondary pollution, which limit their large-scale application in practical engineering.

[0003] Microbial-inorganic semiconductor hybrid materials, as an emerging environmental remediation technology, have attracted widespread attention in recent years. These materials, by combining the light absorption characteristics of inorganic semiconductors with the catalytic activity of microorganisms, can effectively promote the separation and migration of photogenerated carriers, theoretically achieving a solar energy conversion efficiency of approximately 20%. This offers a new possibility for solving the problems of slow electron transfer rates and low quantum efficiency in traditional photocatalytic systems. However, several key bottlenecks remain in the practical construction of these systems, such as poor interfacial compatibility between minerals and microorganisms, limited spectral utilization range, and difficulty in controlling redox reaction pathways at the interface. These issues lead to low energy transfer efficiency and difficulty in maintaining microbial activity, severely restricting their application in real-world environments.

[0004] Currently, some studies have attempted to combine electroactive microorganisms with inorganic semiconductor minerals to leverage the extracellular electron transport capabilities of microorganisms to promote the separation of photogenerated charge carriers. However, existing microbial-mineral composite systems still face the following prominent problems: First, the interfacial bonding between microorganisms and minerals largely relies on physical adsorption, resulting in poor interfacial stability, discontinuous electron transport channels, and low transport efficiency. Second, the high charge transfer resistance at the mineral-microorganism interface in existing systems severely limits the effective separation of photogenerated electron-hole pairs, causing the quantum efficiency of the system to be far below the theoretical level. Third, traditional photocatalytic degradation processes typically rely on molecular oxygen as an electron acceptor to generate reactive oxygen species. In anaerobic or low-oxygen environments such as groundwater and deep soil, the degradation efficiency of photocatalytic systems drops sharply, greatly limiting their practical applications.

[0005] Therefore, how to construct a composite material system with a stable mineral-microorganism interface, high electron transfer efficiency, and excellent degradation activity in an anaerobic environment is a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a pollutant degradation material based on the mineral-microorganism interface capacitance effect, its preparation method and application, so as to solve the technical problems in existing microorganism-mineral composite systems, such as poor stability of the mineral-microorganism interface, high charge transfer resistance leading to low carrier separation efficiency, and the sharp decline in degradation efficiency in anaerobic environments due to dependence on molecular oxygen in traditional photocatalytic degradation processes.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a pollutant degradation material based on the mineral-microorganism interface capacitance effect, wherein the degradation material is composed of a semiconductor iron mineral and electroactive microorganisms; the electroactive microorganisms are Shewanella (… Shewanella oneidensis MR-1.

[0008] Preferably, the semiconductor iron mineral and the electroactive microorganism form a heterojunction structure with capacitive properties at the interface; the capacitive properties are manifested in that the equivalent circuit of the electrochemical impedance spectroscopy of the degradation material conforms to... R s ( Q ( R ct C The model has an interface capacitance of 8.1~13.2 μF·cm. -2 .

[0009] Preferably, the semiconductor iron mineral is selected from at least one of hematite and goethite.

[0010] Preferably, the particle size of the semiconductor iron mineral ranges from 200 to 400 mesh; the mass ratio of the semiconductor iron mineral to the electroactive microorganism is 1:(0.5~2), wherein the electroactive microorganism has an OD concentration of [missing value]. 600 The bacterial cells were obtained by centrifugation of bacterial solutions with a concentration of 0.8~1.2.

[0011] The present invention also provides a method for preparing the above-mentioned pollutant degradation material, comprising the following steps: inoculating Shewanella MR-1 into a nutrient medium for culture, collecting the bacterial cells, and freeze-drying to obtain bacterial powder; mixing sterilized semiconductor iron mineral powder with the bacterial powder in PBS buffer solution and co-culturing under anaerobic conditions with shaking; collecting the precipitate, washing and freeze-drying to obtain the pollutant degradation material.

[0012] Preferably, the nutrient culture medium contains 15-25 g / L peptone, 5-15 g / L yeast extract and 5-10 g / L sodium chloride; the culture conditions are: temperature 25-28 ℃, rotation speed 180-200 rpm, and time 12-36 h.

[0013] Preferably, the temperature for the oscillating co-culture is 25~35 ℃, the shaking speed is 140~180 rpm, and the co-culture time is 24~72 h.

[0014] The present invention also provides the application of the above-mentioned pollutant degradation materials or the degradation materials prepared by the above-mentioned preparation method in the degradation of organic pollutants; the organic pollutants include tetracycline antibiotics.

[0015] Preferably, the process of degrading organic pollutants is carried out under light conditions, with a light intensity of 8000~10000 lux and visible light as the light source.

[0016] Preferably, the process of degrading organic pollutants is carried out under anaerobic conditions, and the dissolved oxygen concentration in the reaction system is less than 0.1 mg / L.

[0017] The beneficial effects of this invention are: Under light irradiation, the Shewanella MR-1 and iron oxide composite system constructed in this invention exhibits excellent antibiotic removal capabilities. Experimental results show that the hematite / Shewanella MR-1 composite material achieves a degradation rate of approximately 86% for tetracycline hydrochloride under 120 minutes of light irradiation, with a degradation rate constant of 0.016 min. -1 The degradation rates were 3.2 times and 5.33 times that of single hematite and single bacterial cells, respectively; the degradation rate of the goethite / Shewanella MR-1 composite material reached approximately 84%, with a degradation rate constant of 0.015 min. -1 The removal rates were 7.5 times and 5 times higher than those of single goethite and single bacterial cells, respectively. This system can consistently achieve a removal rate of over 84% for antibiotics, rapidly and effectively reducing antibiotic concentrations and significantly mitigating the risks these pollutants pose to the ecological environment, providing a highly efficient solution for water purification.

[0018] In this invention, the interfacial capacitance formed between Shewanella MR-1 and iron oxides effectively optimizes the electron transport pathway, significantly enhances the separation and migration efficiency of photogenerated carriers, improves light energy utilization, and provides continuous reaction power for pollutant degradation. Quantitative analysis shows that the charge transfer resistance of the hematite system is significantly reduced from 19.22 kΩ·cm for a single mineral. -2 Significantly reduced to 0.48 kΩ·cm -2 The charge transfer resistance of the goethite system is 28.44 kΩ·cm for a single mineral. -2 Significantly reduced to 1.13 kΩ·cm -2 The interface capacitance is as high as 8.1~13.2 μF·cm. -2 This indicates that the mineral-microbe interface can serve as a highly efficient electron transport channel.

[0019] This invention discovers and utilizes the "dichotomy effect" of mineral-microorganism interfacial capacitance. Specifically, different types of iron minerals, when combined with Shewanella MR-1, exhibit significantly different regulatory effects of their interfacial capacitance on photocatalytic degradation pathways: when the semiconductor iron mineral is goethite, the interfacial capacitance primarily enhances the hole oxidation pathway, promoting the direct oxidative degradation of pollutants by photogenerated holes; when the semiconductor iron mineral is hematite, the interfacial capacitance primarily enhances the direct electron reduction pathway, promoting the direct reduction degradation of pollutants by photogenerated electrons. This discovery provides a theoretical basis and material foundation for targeted selection of degradation pathways for different types of pollutants.

[0020] The pollutant degradation material provided by this invention still exhibits excellent degradation activity under anaerobic conditions, breaking through the dependence of traditional photocatalytic systems on molecular oxygen. This system has good environmental adaptability and is suitable for various water pollution treatment scenarios, including anaerobic or low-oxygen environments such as groundwater and deep soil, significantly expanding the practical application scope of photocatalytic technology.

[0021] The preparation method provided by this invention is simple in process, uses natural iron minerals and microorganisms as raw materials, is environmentally friendly, does not produce secondary pollution, has mild preparation conditions, and is easy to apply on a large scale. It provides an innovative technical path for the green treatment of persistent organic pollutants such as antibiotics. Attached Figure Description

[0022] Figure 1 This is a transmission electron microscope (TEM) image of the composite material in Experimental Example 1. Where a represents Fe2O3 (hematite) / S. oneidensis TEM image of MR-1 composite material; b represents FeOOH (goethite) / S. oneidensis TEM image of MR-1 composite material. The yellow dashed line in the image represents the heterojunction structure formed by the tight bonding between the semiconductor iron mineral and the microorganism.

[0023] Figure 2 The figures show the electrochemical impedance spectroscopy (EIS) and equivalent circuit fitting data for each system in Experimental Example 2. Specifically, a) is the Bode plot of Fe₂O₃ and its composite system; b) is the Bode plot of FeOOH and its composite system; and c) is the equivalent circuit fitting model diagram for the single mineral system and the composite system (single mineral system uses...). R s (QR ct ) Model, composite system adopts R s (Q(R ct C)) (Dual time constant model); d is the fitting result of each system. Q Value (constant phase angle element) andC A histogram of values ​​(interface capacitance); e represents the charge transfer resistance of the Fe2O3 system. (R ct ) Fitted histogram; f is the charge transfer resistance of the FeOOH system. (R ct ) Fit a histogram.

[0024] Figure 3 For Fe2O3 in Experimental Example 3, S. oneidensis MR-1 single component and Fe2O3 / S. oneidensis The degradation kinetics curves of tetracycline hydrochloride by the MR-1 composite material; in the figure, the dashed line with the moon icon represents the adsorption and degradation under dark conditions (control group), and the solid line with the sun icon represents the degradation under visible light conditions.

[0025] Figure 4 For example 3, FeOOH, S. oneidensis MR-1 single component and FeOOH / S. oneidensis The degradation kinetics curves of tetracycline hydrochloride by the MR-1 composite material; in the figure, the dashed line with the moon icon represents the adsorption and degradation under dark conditions (control group), and the solid line with the sun icon represents the degradation under visible light conditions. Detailed Implementation

[0026] This invention provides a pollutant degradation material based on the mineral-microorganism interface capacitance effect, wherein the degradation material is composed of a semiconductor iron mineral and electroactive microorganisms; the electroactive microorganisms are Shewanella (… Shewanella oneidensis MR-1 (ATCC 700550). Shewanella MR-1 possesses excellent extracellular electron transport capabilities, enabling efficient electron exchange with external electron acceptors. When combined with semiconductor iron minerals, its extracellular electron transport channels couple with the electronic energy levels on the mineral surface, constructing an interfacial capacitor structure with electron storage and release functions at the interface. This significantly promotes the separation and migration of photogenerated charge carriers, reduces charge transfer resistance, and improves photocatalytic degradation efficiency.

[0027] In this invention, the semiconductor iron mineral and the electroactive microorganisms form a heterojunction structure with capacitive properties at the interface. The capacitive properties are manifested in the fact that the electrochemical impedance spectroscopy (EIS) Nyquist plot of the degradation material exhibits a double capacitive arc characteristic, and its equivalent circuit conforms to… R s (Q(R ct C))Model. The additional capacitor element C in the equivalent circuit of the composite system indicates that a capacitor layer with charge storage and release function is formed at the mineral-microorganism interface. This capacitor layer can effectively promote the separation of photogenerated electron-hole pairs and reduce the interfacial charge transfer resistance.

[0028] In this invention, the semiconductor iron mineral is preferably selected from at least one of hematite (α-Fe₂O₃) and goethite (FeOOH). As a light-absorbing component, the semiconductor iron mineral has a suitable band gap, enabling it to effectively absorb visible light. Under illumination, it can generate photogenerated electron-hole pairs, providing reactive species for the redox degradation of pollutants. Furthermore, it is widely distributed in the natural environment, inexpensive, and environmentally friendly. The interfacial capacitance between the hematite system and the goethite system exhibits significant differences in its regulatory effect on the degradation pathway, allowing for the selection of a suitable mineral type based on the properties of the target pollutant.

[0029] In this invention, the preferred particle size range of the semiconductor iron mineral is 200-400 mesh. In this invention, the mineral particle size has a significant impact on the interface construction of the composite material. If the particle size is too large, the specific surface area is insufficient, limiting the contact area with microorganisms and hindering the formation of interfacial capacitance; if the particle size is too small, the mineral particles are prone to agglomeration and are difficult to recover. A particle size range of 200-400 mesh provides sufficient specific surface area, which is beneficial for the attachment of microorganisms to the mineral surface and the construction of interfacial heterostructures.

[0030] In this invention, the electroactive microorganisms are preferably those with an OD concentration of [missing information]. 600 The bacterial cells obtained by centrifugation of bacterial suspension with an OD value of 0.8~1.2 are more preferably OD values ​​of 0.8~1.2. 600 =1.0. OD 600 =0.8~1.2 corresponds to the bacterial cells being in the late logarithmic growth phase to the early stationary phase. During this stage, the bacterial cells exhibit strong metabolic activity and high expression levels of extracellular electron transport proteins, which is conducive to the formation of stable electron transport channels with the mineral interface. OD 600 If the OD is too low, the number of bacteria will be insufficient, and the interfacial capacitance effect will be weak; 600 If the concentration is too high, the bacteria will enter a period of decline, their metabolic activity will decrease, and it will be detrimental to the construction of the complex system.

[0031] In this invention, the preferred mass ratio of the semiconductor iron mineral to the electroactive microorganisms is 1:(0.5~2), more preferably 1:1. The mass ratio of mineral to microorganisms directly affects the construction effect of the interfacial capacitance. When the proportion of microorganisms is too low, the microbial coverage on the mineral surface is insufficient, and the interfacial capacitance effect is not significant; when the proportion of microorganisms is too high, excessive bacterial accumulation hinders light irradiation on the mineral surface, reducing the generation efficiency of photogenerated carriers.

[0032] The present invention also provides a method for preparing the above-mentioned pollutant degradation material, comprising the following steps: inoculating Shewanella MR-1 into a nutrient medium for culture, collecting the bacterial cells, and freeze-drying to obtain bacterial powder; mixing sterilized semiconductor iron mineral powder with the bacterial powder in PBS buffer solution and co-culturing under anaerobic conditions with shaking; collecting the precipitate, washing and freeze-drying to obtain the pollutant degradation material.

[0033] In this invention, the specific steps for culturing Shewanella MR-1 are as follows: Shewanella MR-1 is inoculated into a nutrient medium for activation culture. The nutrient medium preferably contains 15-25 g / L peptone, 5-15 g / L yeast extract, and 5-10 g / L sodium chloride; more preferably, it contains 20 g / L peptone, 10 g / L yeast extract, and 5 g / L sodium chloride. In this invention, the activated strain is inoculated into fresh nutrient medium at a volume ratio of 10% (i.e., the seed culture volume accounts for 10% of the total culture medium volume, v / v) for primary culture. The preferred culture conditions are: temperature 25-28 ℃, more preferably 28 ℃; rotation speed 180-200 rpm, more preferably 180 rpm; and culture time 12-36 h, more preferably 24 h.

[0034] In this invention, the preferred method for collecting the bacterial cells is centrifugation of the bacterial solution. The centrifugation conditions are preferably: a rotation speed of 6000-8000 rpm, more preferably 8000 rpm; a time of 8-15 min, more preferably 10 min; and a temperature of 4 °C. The centrifuged bacterial cells are then freeze-dried to obtain bacterial powder for later use.

[0035] In this invention, the semiconductor iron mineral powder needs to be sterilized before use to avoid interference from microbial contamination in the construction of the composite system. The preferred sterilization method is high-pressure steam sterilization, with sterilization conditions preferably at 121°C for 15-20 minutes.

[0036] In this invention, sterilized semiconductor iron mineral powder and bacterial powder are mixed in PBS buffer solution and co-cultured under anaerobic conditions with shaking. The preferred mass ratio of semiconductor iron mineral powder to bacterial powder is 1:(0.5~2), more preferably 1:1. The preferred temperature for the shaking co-culture is 25~35 ℃, more preferably 28~32 ℃; the preferred shaking speed is 140~180 rpm, more preferably 160 rpm; and the preferred co-culture time is 24~72 h, more preferably 48 h. In this invention, anaerobic conditions facilitate the initiation of extracellular electron transport metabolic pathways by Shewanella MR-1, promoting interfacial electron exchange between microorganisms and minerals, thereby constructing a heterojunction structure with capacitive properties at the interface.

[0037] In this invention, after co-culturing, the mixed sample is subjected to solid-liquid separation. The preferred method for solid-liquid separation is centrifugation, with the following conditions: rotation speed 6000-8000 rpm, more preferably 8000 rpm; time 8-15 min, more preferably 10 min; and temperature preferably 4 °C. After collecting the composite precipitate, it is washed 2-3 times with PBS buffer or deionized water to remove residual culture medium components and unbound bacterial cells. The washed sample is then freeze-dried to obtain the pollutant degradation material.

[0038] This invention also provides the application of the above-mentioned pollutant-degrading materials or the above-mentioned preparation methods in the degradation of organic pollutants. The organic pollutants include tetracycline antibiotics, preferably tetracycline hydrochloride.

[0039] In this invention, the degradation of organic pollutants is preferably carried out under light irradiation. The light intensity is preferably 8000~10000 lux, more preferably 10000 lux. The light source is preferably visible light. Semiconductor iron minerals generate photogenerated electron-hole pairs under visible light irradiation, achieving efficient charge separation through the interfacial capacitance structure. The generated active species (holes or electrons) oxidize or reduce the degradation of antibiotic molecules.

[0040] In this invention, the process of degrading organic pollutants is preferably carried out under anaerobic conditions, and the dissolved oxygen concentration in the reaction system is preferably less than 0.1 mg / L.

[0041] In this invention, the mass ratio of the pollutant-degrading material to the organic pollutant is preferably (4~20):1, more preferably 20:1. The initial concentration of the organic pollutant is preferably 10~50 mg / L, more preferably 10 mg / L. The temperature of the degradation reaction is preferably 25~32 ℃, more preferably 25 ℃. The time of the degradation reaction is preferably 0.5~2 h, more preferably 2 h.

[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Unless otherwise specified, the following embodiments are all conventional methods.

[0044] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0045] The hematite (α-Fe₂O₃) and goethite (FeOOH) used in the following examples were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The Shewanella MR-1 (ATCC 700550) used in the following examples was obtained through commercial purchase.

[0046] Example 1 A pollutant degradation material based on the capacitance effect of the mineral-microorganism interface is composed of a semiconductor iron mineral and electroactive microorganisms. The semiconductor iron mineral is 1.0 g of hematite powder with a particle size of 200 mesh, which has been sterilized. The electroactive microorganism is Shewanella MR-1 bacterial powder, cultured to OD... 600 The bacterial culture with a concentration of 0.8 was collected by centrifugation and freeze-dried, with a dosage of 0.5 g; the mass ratio of semiconductor iron mineral to electroactive microorganism was 1:0.5.

[0047] The method for preparing the pollutant degradation material is as follows: Shewanella MR-1 was removed from a -80 °C glycerol storage tube and inoculated into a nutrient medium for activation. The nutrient medium consisted of 15 g / L peptone, 5 g / L yeast extract, and 5 g / L sodium chloride. The activated strain was inoculated at a 10% inoculation rate (v / v) into the above nutrient medium for primary culture under the following conditions: 25 °C, 180 rpm shaking speed, and 12 h culture time, until the bacterial OD reached the target value. 600 The concentration was increased to 0.8. The obtained bacterial solution was centrifuged at 4 ℃ and 6000 rpm for 8 min, the supernatant was discarded, the bacterial precipitate was collected, and it was freeze-dried to obtain Shewanella MR-1 bacterial powder for later use.

[0048] 1.0 g of hematite powder with a particle size of 200 mesh was sterilized by autoclaving at 121 °C for 15 min, and then mixed with 0.5 g of the prepared Shewanella MR-1 bacterial powder. The mixture was added to PBS buffer solution and co-cultured under anaerobic conditions at 25 °C and 140 rpm for 24 h. After co-culture, the mixed sample was centrifuged at 4 °C and 6000 rpm for 8 min, the composite precipitate was collected, washed twice with PBS buffer, and then freeze-dried to obtain the hematite / Shewanella MR-1 composite material.

[0049] Example 2 A pollutant degradation material based on the capacitance effect of the mineral-microorganism interface is composed of a semiconducting iron mineral and electroactive microorganisms. The semiconducting iron mineral is 1.0 g of goethite powder with a particle size of 200 mesh, which has been sterilized. The electroactive microorganism is Shewanella MR-1 bacterial powder, cultured to OD... 600 The bacterial culture with a concentration of 0.8 was collected by centrifugation and freeze-dried, with a dosage of 0.5 g; the mass ratio of semiconductor iron mineral to electroactive microorganism was 1:0.5.

[0050] The method for preparing the pollutant degradation material is as follows: Shewanella MR-1 was removed from a -80 °C glycerol storage tube and inoculated into a nutrient medium for activation. The nutrient medium consisted of 15 g / L peptone, 5 g / L yeast extract, and 5 g / L sodium chloride. The activated strain was inoculated at a 10% inoculation rate (v / v) into the above nutrient medium for primary culture under the following conditions: 25 °C, 180 rpm shaking speed, and 12 h culture time, until the bacterial OD reached the target value. 600 The concentration was increased to 0.8. The obtained bacterial solution was centrifuged at 4 ℃ and 6000 rpm for 8 min, the supernatant was discarded, the bacterial precipitate was collected, and it was freeze-dried to obtain Shewanella MR-1 bacterial powder for later use.

[0051] 1.0 g of goethite powder with a particle size of 200 mesh was sterilized by autoclaving at 121 °C for 15 min, and then mixed with 0.5 g of the prepared Shewanella MR-1 bacterial powder. The mixture was added to PBS buffer solution and co-cultured under anaerobic conditions at 25 °C and 140 rpm for 24 h. After co-culture, the mixed sample was centrifuged at 4 °C and 6000 rpm for 8 min, the composite precipitate was collected, washed twice with PBS buffer, and then freeze-dried to obtain the goethite / Shewanella MR-1 composite material.

[0052] Example 3 A pollutant degradation material based on the capacitance effect of the mineral-microorganism interface is composed of a semiconductor iron mineral and electroactive microorganisms. The semiconductor iron mineral is 1.0 g of hematite powder with a particle size of 400 mesh, which has been sterilized. The electroactive microorganism is Shewanella MR-1 bacterial powder, cultured to OD... 600 The bacterial culture with a concentration of 1.2 was collected by centrifugation and freeze-dried, with a dosage of 2.0 g; the mass ratio of semiconductor iron mineral to electroactive microorganism was 1:2.

[0053] The method for preparing the pollutant degradation material is as follows: Shewanella MR-1 was removed from a -80 °C glycerol storage tube and inoculated into a nutrient medium for activation. The nutrient medium consisted of 25 g / L peptone, 15 g / L yeast extract, and 10 g / L sodium chloride. The activated strain was inoculated at a 10% inoculation rate (v / v) into the above nutrient medium for primary culture under the following conditions: temperature 28 °C, shaker speed 200 rpm, culture time 36 h, until the bacterial OD reached the target value. 600 The bacterial culture was centrifuged at 4 ℃ and 8000 rpm for 15 min. The supernatant was discarded, and the bacterial precipitate was collected. After freeze-drying, Shewanella MR-1 bacterial powder was obtained for later use.

[0054] 1.0 g of hematite powder with a particle size of 400 mesh was sterilized by autoclaving at 121 °C for 20 min, and then mixed with 2.0 g of the prepared Shewanella MR-1 bacterial powder. The mixture was added to PBS buffer solution and co-cultured under anaerobic conditions at 35 °C and 180 rpm for 72 h. After co-culture, the mixed sample was centrifuged at 4 °C and 8000 rpm for 15 min, the composite precipitate was collected, washed three times with PBS buffer, and then freeze-dried to obtain the hematite / Shewanella MR-1 composite material.

[0055] Example 4 A pollutant degradation material based on the capacitance effect of the mineral-microorganism interface is composed of a semiconducting iron mineral and electroactive microorganisms. The semiconducting iron mineral is 1.0 g of goethite powder with a particle size of 400 mesh, which has been sterilized. The electroactive microorganism is Shewanella MR-1 bacterial powder, cultured to OD... 600 The bacterial culture with a concentration of 1.2 was collected by centrifugation and freeze-dried, with a dosage of 2.0 g; the mass ratio of semiconductor iron mineral to electroactive microorganism was 1:2.

[0056] The method for preparing the pollutant degradation material is as follows: Shewanella MR-1 was removed from a -80 °C glycerol storage tube and inoculated into a nutrient medium for activation. The nutrient medium consisted of 25 g / L peptone, 15 g / L yeast extract, and 10 g / L sodium chloride. The activated strain was inoculated at a 10% inoculation rate (v / v) into the above nutrient medium for primary culture under the following conditions: temperature 28 °C, shaker speed 200 rpm, culture time 36 h, until the bacterial OD reached the target value. 600 The bacterial culture was centrifuged at 4 ℃ and 8000 rpm for 15 min. The supernatant was discarded, and the bacterial precipitate was collected. After freeze-drying, Shewanella MR-1 bacterial powder was obtained for later use.

[0057] 1.0 g of goethite powder with a particle size of 400 mesh was autoclaved at 121 °C for 20 min and then mixed with 2.0 g of Shewanella MR-1 bacterial powder prepared above. The mixture was added to PBS buffer solution and co-cultured under anaerobic conditions at 35 °C and 180 rpm for 72 h. After co-culture, the mixed sample was centrifuged at 4 °C and 8000 rpm for 15 min, the composite precipitate was collected, washed three times with PBS buffer, and then freeze-dried to obtain the goethite / Shewanella MR-1 composite material.

[0058] Example 5 A pollutant degradation material based on the capacitance effect of the mineral-microorganism interface is composed of a semiconductor iron mineral and electroactive microorganisms. The semiconductor iron mineral is 1.0 g of 300-mesh hematite (α-Fe₂O₃) powder, sterilized; the electroactive microorganism is Shewanella MR-1 bacterial powder, cultured to OD₂₀. 600 The bacterial culture with a concentration of 1.0 g was collected by centrifugation and freeze-dried, and the amount used was 1.0 g; the mass ratio of semiconductor iron mineral to electroactive microorganism was 1:1.

[0059] The method for preparing the pollutant degradation material is as follows: Shewanella MR-1 was removed from a -80 °C glycerol storage tube and inoculated into a nutrient medium for activation. The nutrient medium consisted of 20 g / L peptone, 10 g / L yeast extract, and 5 g / L sodium chloride. The activated strain was inoculated at a 10% inoculation rate (v / v) into the above nutrient medium for primary culture under the following conditions: temperature 28 °C, shaker speed 180 rpm, culture time 24 h, until the bacterial OD reached the target value. 600 The bacterial culture was centrifuged at 4 ℃ and 8000 rpm for 10 min, the supernatant was discarded, the bacterial precipitate was collected, and the precipitate was freeze-dried to obtain Shewanella MR-1 bacterial powder for later use.

[0060] 1.0 g of hematite powder with a particle size of 300 mesh was sterilized by autoclaving at 121 °C for 20 min, and then mixed with 1.0 g of Shewanella MR-1 bacterial powder prepared above. The mixture was added to PBS buffer solution and co-cultured under anaerobic conditions at 28 °C and 160 rpm for 48 h. After co-culture, the mixed sample was centrifuged at 4 °C and 8000 rpm for 10 min, the composite precipitate was collected, washed three times with PBS buffer, and then freeze-dried to obtain the hematite / Shewanella MR-1 composite material.

[0061] Example 6 A pollutant degradation material based on the capacitance effect of the mineral-microorganism interface is composed of a semiconducting iron mineral and electroactive microorganisms. The semiconducting iron mineral is 1.0 g of 300-mesh goethite (FeOOH) powder, sterilized; the electroactive microorganism is Shewanella MR-1 bacterial powder, cultured to OD... 600 The bacterial culture with a concentration of 1.0 g was collected by centrifugation and freeze-dried, and the amount used was 1.0 g; the mass ratio of semiconductor iron mineral to electroactive microorganism was 1:1.

[0062] The method for preparing the pollutant degradation material is as follows: Shewanella MR-1 was removed from a -80 °C glycerol storage tube and inoculated into a nutrient medium for activation. The nutrient medium consisted of 20 g / L peptone, 10 g / L yeast extract, and 5 g / L sodium chloride. The activated strain was inoculated at a 10% inoculation rate (v / v) into the above nutrient medium for primary culture under the following conditions: temperature 28 °C, shaker speed 180 rpm, culture time 24 h, until the bacterial OD reached the target value. 600 The bacterial culture was centrifuged at 4 ℃ and 8000 rpm for 10 min, the supernatant was discarded, the bacterial precipitate was collected, and the precipitate was freeze-dried to obtain Shewanella MR-1 bacterial powder for later use.

[0063] 1.0 g of goethite powder with a particle size of 300 mesh was sterilized by autoclaving at 121 °C for 20 min, and then mixed with 1.0 g of Shewanella MR-1 bacterial powder prepared above. The mixture was added to PBS buffer solution and co-cultured under anaerobic conditions at 28 °C and 160 rpm for 48 h. After co-culture, the mixed sample was centrifuged at 4 °C and 8000 rpm for 10 min, the composite precipitate was collected, washed three times with PBS buffer, and then freeze-dried to obtain the goethite / Shewanella MR-1 composite material.

[0064] Experimental Example 1 The morphology of the hematite / Shewanella MR-1 composite material prepared in Example 5 and the goethite / Shewanella MR-1 composite material prepared in Example 6 were observed by transmission electron microscopy (TEM). The results are as follows: Figure 1 As shown in the figure, after anaerobic shaking co-culturing in PBS buffer, Shewanella MR-1 in Examples 5 and 6 were able to adhere tightly to the surface of the corresponding semiconductor iron minerals (hematite or goethite). The figure clearly shows that a tight physical contact (labeled as Heterostructure) is formed between the microbial cell wall and the inorganic mineral lattice, confirming that the preparation process of the present invention successfully constructs a tight biological-inorganic heterostructure composite structure at the mineral-microorganism interface, rather than a simple physical mixture.

[0065] Experimental Example 2 Electrochemical impedance spectroscopy (EIS) was performed on the hematite (α-Fe2O3) / Shewanella MR-1 composite material prepared in Example 5, the goethite (FeOOH) / Shewanella MR-1 composite material prepared in Example 6, and single hematite and single goethite as controls.

[0066] like Figure 2 As shown in c, EIS data for single hematite and single goethite are only applicable to simple single-time-constant models. Rs (QR ct ) The models all exhibit only a single capacitive arc characteristic in their Nyquist plots. However, as... Figure 2 a in Figure 2 As shown in b, the Bode plots of both the hematite / Shewanella MR-1 composite material and the goethite / Shewanella MR-1 composite material exhibit obvious phase angle broadening and bimodal characteristics. The Nyquist plots of both materials show double capacitive arc characteristics, necessitating the use of a dual-time-constant model incorporating an additional capacitor element C. R s (Q(R ct C)) Model fitting description 。

[0067] like Figure 2 As shown in d, e, and f, quantitative fitting analysis indicates that the charge transfer resistance of the hematite system increases from 19.22 kΩ·cm for a single mineral. -2 Significantly reduced to 0.48 kΩ·cm -2 The charge transfer resistance of the goethite system is 28.44 kΩ·cm for a single mineral. -2 Significantly reduced to 1.13 kΩ·cm -2 Meanwhile, a large capacitance value was successfully fitted at the interface, with the interface capacitance (C) of Example 5 (hematite composite system) reaching approximately 9.5 μF·cm. -2 The interfacial capacitance (C) of Example 6 (goethite composite system) reached approximately 8.1 μF·cm. -2 This result directly confirms the existence of efficient electron transfer and storage channels at the microbial-mineral interface.

[0068] Experimental Example 3 The hematite / Shewanella MR-1 composite material prepared in Example 5 and the goethite / Shewanella MR-1 composite material prepared in Example 6 were used to conduct photodegradation experiments on tetracycline hydrochloride. Simultaneously, single hematite, single goethite, and single Shewanella MR-1 cells were used as control groups, and dark conditions were used as a blank control.

[0069] The degradation experiment was conducted as follows: 5 mg of sample was dispersed in 25 mL of tetracycline hydrochloride aqueous solution with an initial concentration of 10 mg / L, with a mass ratio of degradation material to pollutant of 20:1. The dissolved oxygen concentration in the reaction system was below 0.1 mg / L, the temperature was maintained at 25 ℃, and the pH was 7.0. Visible light was used for irradiation at an intensity of 10000 lux. Samples were taken at timed intervals of 0, 20, 40, 60, 80, 100, and 120 min. After filtration through a 0.22 μm filter membrane, the residual concentration of tetracycline hydrochloride was determined using UV-Vis spectrophotometry, and the degradation rate was calculated.

[0070] The degradation kinetics curves of tetracycline hydrochloride under light conditions for hematite / Shewanella MR-1 composite material, hematite alone, and Shewanella MR-1 alone are shown below. Figure 3 As shown, the hematite / Shewanella MR-1 composite material achieved a degradation rate of approximately 86% for tetracycline hydrochloride within a 120-minute light exposure period, significantly higher than that of hematite alone (approximately 50%) and shewanella alone (approximately 26%). Kinetic analysis indicated that its degradation rate constant was 0.016 min. -1 The values ​​were: single hematite (0.005 min). -1 ) and single bacterial cells (0.003 min) -1 The degradation activity was 3.2 times and 5.33 times that of tetracycline hydrochloride, respectively. Under dark conditions, none of the samples showed significant degradation activity against tetracycline hydrochloride, indicating that the degradation process was photo-driven. Analysis of the degradation products revealed that the interfacial capacitance of the hematite / Shewanella MR-1 composite material mainly enhanced the direct electron reduction pathway, promoting the direct reduction degradation of tetracycline hydrochloride by photogenerated electrons.

[0071] The degradation kinetics curves of tetracycline hydrochloride under light conditions for goethite / Shewanella MR-1 composite material, goethite alone, and Shewanella MR-1 alone are shown below. Figure 4 As shown, the goethite / Shewanella MR-1 composite material achieved a degradation rate of approximately 84% for tetracycline hydrochloride within a 120-minute light exposure period, significantly higher than that of goethite alone (approximately 25%). Kinetic analysis indicated that its degradation rate constant was 0.015 min. -1 The values ​​were: single goethite (0.002 min). -1 The degradation activity was 7.5 times and 5 times that of single bacterial cells, respectively. Under dark conditions, none of the samples showed significant degradation activity against tetracycline hydrochloride. Analysis of degradation products revealed that the interfacial capacitance of the goethite / Shewanella MR-1 composite material mainly enhanced the hole oxidation pathway, promoting the oxidative degradation of tetracycline hydrochloride by photogenerated holes.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A pollutant degradation material based on the mineral-microorganism interface capacitance effect, characterized in that, The degradation material is composed of a composite of semiconductor iron minerals and electroactive microorganisms; The electroactive microorganism is Shewanella ( Shewanella oneidensis MR-1.

2. The pollutant degradation material according to claim 1, characterized in that, The semiconductor iron mineral and the electroactive microorganism form a heterojunction structure with capacitive properties at the interface. The capacitance characteristic is manifested as follows: the equivalent circuit of the electrochemical impedance spectroscopy of the degradation material conforms to... R s ( Q ( R ct C The model has an interface capacitance of 8.1~13.2 μF·cm. -2 .

3. The pollutant degradation material according to claim 1, characterized in that, The semiconductor iron mineral is selected from at least one of hematite and goethite.

4. The pollutant degradation material according to any one of claims 1 to 3, characterized in that, The semiconductor iron mineral has a particle size range of 200-400 mesh; the mass ratio of the semiconductor iron mineral to the electroactive microorganism is 1:(0.5-2), wherein the electroactive microorganism has a concentration of OD 600 The bacterial cells were obtained by centrifugation of bacterial solutions with a concentration of 0.8~1.

2.

5. A method for preparing a pollutant-degrading material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Shewanella MR-1 was inoculated into a nutrient medium and cultured. The bacterial cells were collected and freeze-dried to obtain bacterial powder. The sterilized semiconductor iron mineral powder was mixed with the bacterial powder in PBS buffer solution and co-cultured under anaerobic conditions with shaking. The precipitate is collected, washed, and freeze-dried to obtain pollutant-degraded materials.

6. The preparation method according to claim 5, characterized in that, The nutrient culture medium contains 15-25 g / L peptone, 5-15 g / L yeast extract and 5-10 g / L sodium chloride; the culture conditions are: temperature 25-28 ℃, rotation speed 180-200 rpm, and time 12-36 h.

7. The preparation method according to claim 5, characterized in that, The temperature for the oscillating co-culture was 25~35 ℃, the shaking speed was 140~180 rpm, and the co-culture time was 24~72 h.

8. The application of the pollutant-degrading material according to any one of claims 1 to 4 or the preparation method according to any one of claims 5 to 7 in the degradation of organic pollutants, characterized in that, The organic pollutants include tetracycline antibiotics.

9. The application according to claim 8, characterized in that, The degradation of organic pollutants takes place under light conditions with an intensity of 8,000 to 10,000 lux and visible light as the light source.

10. The application according to claim 8 or 9, characterized in that, The degradation of organic pollutants is carried out under anaerobic conditions, and the dissolved oxygen concentration in the reaction system is less than 0.1 mg / L.

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