Iron-reducing bacteria sulfidation modified zero-valent iron material, preparation method and application thereof

Abstract

The application provides a preparation method of iron-reducing bacteria sulfidation modified zero-valent iron material, and compared with the prior art, the application utilizes a microbial reduction method to co-culture Shewanella with iron powder and a sulfur source to synthesize the sulfidation modified zero-valent iron material, realizes reduction of an iron oxide passivation layer, and realizes modification of iron sulfide and a small amount of extracellular polymers of Shewanella on the surface of the zero-valent iron, wherein raw material cost is low, the synthesis method is green and safe, and environment-friendly; and the obtained iron-reducing bacteria sulfidation modified zero-valent iron material has the advantages of large specific surface area, good dispersity and strong electron transfer capacity, the reduction capacity of the material to pollutants is significantly improved, and the material can realize sustainable and efficient removal of pollutants, can efficiently remove various halogenated organic matters and heavy metal pollutants in water, can be widely applied to wastewater treatment, and has wide practical application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental pollution control, and particularly relates to a zero-valent iron material modified by iron-reducing bacteria sulfuration, a preparation method thereof and application thereof. BACKGROUND

[0002] With the development of industry, water pollution problems are increasingly prominent. After the discharge of wastewater containing refractory pollutants such as halogenated organic pollutants and heavy metals, the safety of water environment and the recyclability of water resources are seriously endangered, which poses a threat to the ecological environment and human health. Therefore, the control and treatment of water pollution are of great significance to the sustainable development of the environment and society. Zero-valent iron (ZVI) is widely used in the removal of environmental pollutants due to its wide source, low price and strong reduction performance.

[0003] However, there are certain limitations in the practical application of zero-valent iron. The surface of zero-valent iron is easily oxidized to form an iron oxide passivation layer, which limits electron transfer and inhibits reaction activity. To solve the above problems, surface modification of zero-valent iron, including destruction of the iron oxide passivation layer and surface modification, has become a research focus. Common methods for destroying the passivation layer include chemical addition of reducing agents or chelating agents and microbial reduction; surface modification strategies include heteroatom doping and functional group modification, such as the synthesis of sulfurized zero-valent iron by chemical means to improve its reaction activity. Therefore, it is crucial to destroy the passivation layer and modify the surface of zero-valent iron under the premise of green and safe preparation methods to improve the reaction activity of zero-valent iron and expand its environmental applications. SUMMARY

[0004] Therefore, the present application aims to solve the technical problem by providing a zero-valent iron material modified by iron-reducing bacteria sulfuration, a preparation method thereof and application thereof. The present application uses a green, safe and environmentally friendly microbial reduction method to co-culture Shewanella with iron powder and a sulfur source. Through the reduction of the iron oxide passivation layer on the surface of the iron powder by Shewanella and the addition of the sulfur source, the iron sulfide and a small amount of extracellular polymeric substance of Shewanella are modified on the surface of the zero-valent iron to synthesize a sulfur-modified zero-valent iron material. The prepared iron-reducing bacteria sulfuration-modified zero-valent iron material has strong reaction activity for the reduction and removal of pollutants, exhibits high removal efficiency for halogenated organic compounds and heavy metals in water, and is beneficial to application.

[0005] The present application provides a preparation method of a zero-valent iron material modified by iron-reducing bacteria sulfuration, comprising the following steps:

[0006] The Shewanella bacterial suspension, mineral salt liquid medium, carbon source, sulfur source and iron powder are mixed to perform a microbial sulfuration reaction under anaerobic conditions to obtain the zero-valent iron material modified by iron-reducing bacteria sulfuration.

[0007] Preferably, the Shewanella bacterial suspension is prepared according to the following method:

[0008] After the Shewanella strain is cultured in the LB liquid medium, centrifugal separation is performed, and after being dispersed by washing with the mineral salt liquid medium, the Shewanella bacterial suspension is obtained.

[0009] Preferably, the temperature of the culture is 30-35℃; the time of the culture is 16-24h; the rotation speed of the centrifugal separation is 3000-5000rpm; and the time of the centrifugal separation is 10-15min.

[0010] Preferably, the carbon source is selected from sodium lactate; and the sulfur source is selected from one or more of sodium thiosulfate, sodium sulfite and sulfur powder.

[0011] Preferably, the concentration of the carbon source in the reaction system of the microbial sulfidation reaction is 10-40mmol / L.

[0012] The concentration of the sulfur source in the reaction system of the microbial sulfidation reaction is 2-20mmol / L.

[0013] Preferably, the OD of the Shewanella bacterial suspension mixed with the mineral salt liquid medium is 0.2-0.5. 600

[0014] The concentration of the iron powder in the reaction system of the microbial sulfidation reaction is 4-8g / L.

[0015] Preferably, the mineral salt liquid medium comprises 0.4-0.5g / L NaCl, 0.2-0.3g / L (NH4)2SO4, 0.2-0.3g / L KH2PO4, 0.2-0.3g / L K2HPO4, 0.4-0.5g / L MgSO4·7H2O, 8-12mL / L trace mineral stock solution and 40-60mM HEPES buffer, and the pH is adjusted to 6.9-7.4 by using a NaOH solution.

[0016] Preferably, the temperature of the microbial sulfidation reaction is 30-35℃; and the time of the microbial sulfidation reaction is 6-40h.

[0017] The application further provides an iron-reducing bacteria sulfidation-modified zero-valent iron material prepared by the preparation method.

[0018] The application further provides an application of the iron-reducing bacteria sulfidation-modified zero-valent iron material in wastewater treatment.

[0019] ​The application provides a preparation method of iron-reducing bacteria sulfidation modified zero-valent iron material, comprising the following steps: mixing Shewanella bacterial suspension, mineral salt liquid medium, carbon source, sulfur source and iron powder under anaerobic conditions to perform a microbial sulfidation reaction, so as to obtain the iron-reducing bacteria sulfidation modified zero-valent iron material. Compared with the prior art, the application utilizes a microbial reduction method to co-culture Shewanella iron-reducing bacteria, iron powder and sulfur source to synthesize the sulfidation modified zero-valent iron material, realizes reduction of an iron oxide passivation layer, and realizes modification of iron sulfide and a small amount of extracellular polymers of Shewanella on the surface of the zero-valent iron, so that the raw material cost is low, the synthesis method is green and safe, and the environment is friendly; and the obtained iron-reducing bacteria sulfidation modified zero-valent iron material has the advantages of large specific surface area, good dispersity and strong electron transfer capacity, the reduction capacity for pollutants is significantly improved, the sustainable and efficient removal of pollutants can be realized, a variety of halogenated organic pollutants and heavy metals in water bodies can be efficiently and removed, the iron-reducing bacteria sulfidation modified zero-valent iron material can be widely applied to wastewater treatment, and has wide practical application potential.

[0020] Experiments show that the removal effect of the iron-reducing bacteria sulfidation modified zero-valent iron material prepared in the application on halogenated organic pollutants and heavy metals in water bodies is better than that of unmodified iron powder raw materials. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a process flow diagram for preparing the iron-reducing bacteria sulfidation modified zero-valent iron material in Example 1 of the application.

[0022] Figure 2 It is a scanning electron microscope (SEM) image and an energy spectrum (EDS) image of the iron-reducing bacteria sulfidation modified zero-valent iron material prepared in Example 1 of the application.

[0023] Figure 3 It is an X-ray photoelectron spectroscopy (XPS) image of an S2p orbital of the iron-reducing bacteria sulfidation modified zero-valent iron material prepared in Example 1 of the application.

[0024] Figure 4 It is a removal effect diagram of the iron-reducing bacteria sulfidation modified zero-valent iron and iron powder on tetrabromobisphenol A (TBBPA) prepared in Examples 1-3 of the application.

[0025] Figure 5 It is a removal effect diagram of the iron-reducing bacteria sulfidation modified zero-valent iron and iron powder on hexavalent chromium (Cr(VI)) prepared in Examples 1-3 of the application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0027] The present application provides a preparation method of iron-reducing bacteria sulfidation modified zero-valent iron material, comprising the following steps: mixing Shewanella bacterial suspension, mineral salt liquid medium, carbon source, sulfur source and iron powder under anaerobic conditions to carry out microbial sulfidation reaction, to obtain the iron-reducing bacteria sulfidation modified zero-valent iron material.

[0028] The iron-reducing bacteria sulfidation modified zero-valent iron material provided by the present application is prepared by co-culturing Shewanella and iron powder and sulfur source, magnetic separation and freeze-drying. In the present application, the iron oxide passivation layer on the surface of the iron powder is reduced by Shewanella, and the sulfur source is added to form iron sulfide modified on the surface of the zero-valent iron to improve the reaction activity. The iron-reducing bacteria sulfidation modified zero-valent iron material can be added to a water solution containing pollutants for the reduction and removal of pollutants, and especially, the iron-reducing bacteria sulfidation modified zero-valent iron material obtained by the present application can efficiently reduce and remove halogenated organic compounds and heavy metals in water, which has broad practical application potential.

[0029] Referring to Figure 1 , Figure 1 A specific preparation process schematic diagram of the iron-reducing bacteria sulfidation modified zero-valent iron material provided by the present application is provided. Figure 1 As shown in the figure, the present application realizes the modification of iron sulfide and a small amount of extracellular polymers of Shewanella on the surface of zero-valent iron by co-culturing Shewanella and iron powder and sulfur source, and by microbial reduction method in an inert gas atmosphere.

[0030] In the present application, there is no special limitation on the source of all raw materials, which can be purchased on the market.

[0031] In the present application, the Shewanella strain suspension is prepared by the following method: after culturing the Shewanella strain in LB liquid medium, centrifugal separation, and washing and dispersing with mineral salt liquid medium, the Shewanella strain suspension is obtained; the LB liquid medium is the LB liquid medium known to those skilled in the art, and there is no special limitation, and in the present application, it preferably comprises 8-15 g / L proteose peptone, 3-8 g / L yeast extract, and 3-8 g / L sodium chloride, more preferably comprises 8-12 g / L proteose peptone, 4-6 g / L yeast extract, and 4-6 g / L sodium chloride, and more preferably comprises 10 g / L proteose peptone, 5 g / L yeast extract, and 5 g / L sodium chloride; the proteose peptone is preferably tryptone; the pH value of the LB liquid medium is preferably 6.8-7.4, more preferably 6.9-7.2, and more preferably 7; the LB liquid medium is preferably a high-temperature sterilized medium; the high-temperature sterilization temperature is preferably 120-125°C, more preferably 121°C; the high-temperature sterilization time is preferably 15-25 min, more preferably 20 min; the culture is preferably carried out under aerobic conditions; the culture temperature is preferably 30-35°C; the culture time is 16-24 h, more preferably 16-20 h, and more preferably 17-18 h; the centrifugal separation speed is preferably 3000-5000 rpm, more preferably 3500-4500 rpm, and more preferably 4000 rpm; the centrifugal separation time is preferably 10-15 min; the mineral salt liquid medium preferably comprises 0.4-0.5 g / L NaCl, 0.2-0.3 g / L (NH4)2SO4, 0.2-0.3 g / L KH2PO4, 0.2-0.3 g / L K2HPO4, 0.4-0.5 g / L MgSO4·7H2O, 8-12 mL / L trace mineral stock solution, and 40-60 mM HEPES buffer, more preferably comprises 0.44-0.48 g / L NaCl, 0.2-0.25 g / L (NH4)2SO4, 0.2-0.25 g / L KH2PO4, 0.2-0.25 g / L K2HPO4, 0.44-0.48 g / L MgSO4·7H2O, 8-12 mL / L trace mineral stock solution, and 45-55 mM HEPES buffer, more preferably comprises 0.45-0.46 g / L NaCl, 0.22-0.23 g / L (NH4)2SO4, 0.22-0.23 g / L KH2PO4, 0.22-0.23 g / L K2HPO4, 0.45-0.46 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, and 50 mM HEPES buffer, and most preferably comprises 0.46 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.45-0.46 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, and 50 mM HEPES buffer.46g / L MgSO4·7H2O, 10mL / L trace mineral stock solution and 50mM HEPES buffer; the trace mineral stock solution is well known to those skilled in the art and is not particularly limited, and in the present application, preferably includes 1-2g / L nitrilotriacetic acid (NTA), 0.05-0.15g / L MnCl2·4H2O, 0.2-0.4g / L FeSO4·7H2O, 0.15-0.2g / L CoCl2·6H2O, 0.05-0.15g / L ZnCl2, 0.01-0.05g / L CuSO4·5H2O, 0.001-0.01g / L KAl(SO4)2·12H2O, 0.001-0.01g / L H3BO3, 0.05-0.15g / L NaMoO4·2H2O, 0.1-0.15g / L NiCl2·6H2O, 0.01-0.05g / L NaWO4·2H2O and 0.05-0.2g / L NaSeO4, more preferably includes 1.4-1.6g / L nitrilotriacetic acid (NTA), 0.08-0.12g / L MnCl2·4H2O, 0.25-0.35g / L FeSO4·7H2O, 0.16-0.18g / L CoCl2·6H2O, 0.08-0.12g / L ZnCl2, 0.03-0.05g / L CuSO4·5H2O, 0.003-0.006g / L KAl(SO4)2·12H2O, 0.003-0.006g / L H3BO3, 0.08-0.1g / L NaMoO4·2H2O, 0.11-0.13g / L NiCl2·6H2O, 0.02-0.04g / L NaWO4·2H2O and 0.08-0.15g / L NaSeO4, and again preferably includes 1.5g / L nitrilotriacetic acid (NTA), 0.1g / L MnCl2·4H2O, 0.3g / L FeSO4·7H2O, 0.17g / L CoCl2·6H2O, 0.1g / L ZnCl2, 0.04g / L CuSO4·5H2O, 0.005g / L KAl(SO4)2·12H2O, 0.005g / L H3BO3, 0.09g / L NaMoO4·2H2O, 0.12g / L NiCl2·6H2O, 0.02g / L NaWO4·2H2O and 0.1g / L NaSeO4; the mineral salt liquid culture medium is preferably adjusted to a pH of 6.9-7.4 using a NaOH solution, more preferably to a pH of 7.0-7.4, again preferably to a pH of 7.1-7.3, and most preferably to a pH of 7.2; the mineral salt liquid culture medium is preferably a high-temperature sterilization treated culture medium; the temperature of the high-temperature sterilization treatment is preferably 120-125 DEG C, more preferably 121 DEG C; the time of the high-temperature sterilization treatment is preferably 15-25 min, more preferably 20 min.

[0032] The Shewanella bacterial suspension, the mineral salt liquid culture medium, the carbon source, the sulfur source and the iron powder are mixed to carry out a microbial sulfuration reaction under anaerobic conditions; in the present application, the Shewanella bacterial suspension, the mineral salt liquid culture medium, the carbon source and the sulfur source are preferably mixed first; the amount of the Shewanella bacterial suspension is preferably OD 600The carbon source is preferably sodium lactate; the concentration of the carbon source in the reaction system of the microbial sulfidation reaction is preferably 10-40 mmol / L, more preferably 20-40 mmol / L, and more preferably 20-30 mmol / L; the sulfur source is preferably one or more of sodium thiosulfate, sodium sulfite and sulfur powder; in the present application, sodium thiosulfate, sodium sulfite or sulfur powder is used as an external sulfur source, and the surface of zero-valent iron is modified by iron sulfide through microbial reduction, thereby significantly improving the activity of the zero-valent iron material, wherein the sodium thiosulfate, sodium sulfite or sulfur powder can be analytical pure and in powder form; the concentration of the sulfur source in the reaction system of the microbial sulfidation reaction is preferably 2-20 mmol / L, more preferably 5-15 mmol / L, and more preferably 5-10 mmol / L; after mixing the Shewanella bacterial suspension, the mineral salt liquid medium, the carbon source and the sulfur source, the dissolved oxygen in the system is preferably removed; the method for removing the dissolved oxygen in the system is well known to those skilled in the art and is not particularly limited, and in the present application, the dissolved oxygen in the system is preferably removed by exposure to a protective atmosphere; the protective atmosphere can be any protective atmosphere known to those skilled in the art and is not particularly limited, and in the present application, the protective atmosphere is preferably nitrogen; then iron powder is added and mixed to perform microbial sulfidation reaction under anaerobic conditions; the present application does not have special limitations on the particle size, morphology, purity and storage time of the iron powder, and any commercially available iron powder can be used; the iron powder is preferably micron-sized iron powder and / or nano-sized iron powder; in some embodiments provided by the present application, the particle size of the iron powder is preferably 200 nm; the concentration of the iron powder in the reaction system of the microbial sulfidation reaction is preferably 4-8 g / L, more preferably 4-7 g / L, and more preferably 5-6 g / L; the temperature of the microbial sulfidation reaction is preferably 30-35 DEG C; the time of the microbial sulfidation reaction is preferably 6-40 h, and more preferably 6-30 h; in some embodiments provided by the present application, the time of the microbial sulfidation reaction is specifically 24 h, 6 h, 12 h, 18 h or 30 h; the microbial sulfidation reaction is preferably performed under shaking conditions. In the present application, unless otherwise specified, the reaction system of the microbial sulfidation reaction refers to the composition of each substance when the reaction has not started or has just started. During the microbial sulfidation reaction, a small amount of iron powder is dissolved to produce divalent iron, and the solid trivalent iron oxide on the surface of the iron powder is reduced by bacteria to produce divalent iron in solid or dissolved state, which reacts with the negative divalent sulfur reduced by bacteria to produce iron sulfide coated on the surface of the material.

[0033] After the reaction, the iron-reducing bacteria sulfur-modified zero-valent iron material is preferably collected by magnetic separation in a protective atmosphere; the protective atmosphere can be any protective atmosphere known to those skilled in the art, and is not particularly limited, and in the present application, nitrogen is preferred; in the present application, the magnetic separation is preferably specifically placing a magnet at the bottom of the reaction container to separate the material from the solution by magnetic powder; after magnetic separation, the iron-reducing bacteria sulfur-modified zero-valent iron material is preferably washed and dried; the washing is preferably performed using deoxygenated water; the number of times of washing is preferably 2-4, more preferably 3; the drying is preferably vacuum freeze-drying; the temperature of the vacuum freeze-drying is preferably -40 to -50 DEG C; the vacuum degree of the vacuum freeze-drying is preferably 5-10 Pa; and the time of the vacuum freeze-drying is preferably 10-30 h.

[0034] The present application utilizes the microbial reduction method to co-culture Shewanella with iron powder and a sulfur source to synthesize a sulfur-modified zero-valent iron material, realizes reduction of the iron oxide passivation layer, and realizes modification of the iron sulfide and a small amount of extracellular polymer of Shewanella on the surface of the zero-valent iron, has low raw material cost, a green and safe synthesis method, and is environmentally friendly; and the obtained iron-reducing bacteria sulfur-modified zero-valent iron material has the advantages of large specific surface area, good dispersity, and strong electron transfer capacity, significantly improves the reduction capacity for pollutants, can realize sustainable and efficient removal of pollutants, can efficiently reduce and remove various halogenated organic compounds and heavy metals and other pollutants in water, can be widely applied in wastewater treatment, and has broad practical application potential.

[0035] The present application also provides an iron-reducing bacteria sulfur-modified zero-valent iron material prepared by the above preparation method, wherein the iron-reducing bacteria sulfur-modified zero-valent iron material has zero-valent iron as a core; and the surface of the zero-valent iron is wrapped with iron-sulfur oxide and microbial extracellular polymer.

[0036] The iron-reducing bacteria sulfur-modified zero-valent iron material provided by the present application is prepared by reducing the iron oxide passivation layer on the surface of iron powder by Shewanella and forming iron sulfide on the surface of the zero-valent iron by an additional sulfur source. The iron-reducing bacteria sulfur-modified zero-valent iron material provided by the present application has high reduction activity, can efficiently reduce and remove halogenated organic compounds and heavy metals and other pollutants in water, and is beneficial to application in wastewater treatment.

[0037] According to the present application, the particle size of the iron-reducing bacteria sulfur-modified zero-valent iron material is preferably nanoscale.

[0038] According to the present application, the iron-reducing bacteria sulfur-modified zero-valent iron material is preferably irregular spherical structure.

[0039] The present application also provides application of the above iron-reducing bacteria sulfur-modified zero-valent iron material in wastewater treatment.

[0040] The pollutants in the wastewater are preferably halogenated organic compounds and / or heavy metal pollutants, including but not limited to tetrabromobisphenol A and / or hexavalent chromium.

[0041] The application further provides a method for treating wastewater, comprising the following steps: mixing the above-mentioned zero-valent iron material modified by sulfurization of iron-reducing bacteria with wastewater to be treated for treatment.

[0042] According to the application, the amount of the zero-valent iron material modified by sulfurization of iron-reducing bacteria is preferably 1-2 g / L.

[0043] According to the application, the concentration of pollutants in the wastewater to be treated is preferably 5-20 ppm; in some embodiments provided by the application, the concentration of pollutants in the wastewater to be treated is specifically 10 ppm; the pollutants in the wastewater to be treated are preferably halogenated organic compounds and / or heavy metal pollutants, including but not limited to tetrabromobisphenol A and / or hexavalent chromium.

[0044] According to the application, the pH value of the system after mixing the zero-valent iron material modified by sulfurization of iron-reducing bacteria with the wastewater to be treated is preferably 3-9; in some embodiments provided by the application, the pH value of the system after mixing the zero-valent iron material modified by sulfurization of iron-reducing bacteria with the wastewater to be treated is specifically 7, 3 or 9.

[0045] According to the application, the temperature of the treatment is preferably 15-30℃, more preferably 20-30℃, and more preferably 25℃; the treatment is preferably carried out under shaking; the rotating speed of the shaking is preferably 100-300 rpm, more preferably 150-250 rpm, and more preferably 160-200 rpm.

[0046] In order to further illustrate the application, the following embodiments are used to describe the zero-valent iron material modified by sulfurization of iron-reducing bacteria, the preparation method thereof and the application thereof in detail.

[0047] The reagents used in the following examples are commercially available; the particle size of the iron powder used in the examples is 200 nm; the sodium thiosulfate, sodium sulfite or sulfur powder used in the examples can be analytical pure, in powder form; the composition of the LB liquid medium used in the examples is 10 g / L tryptone, 5 g / L yeast extract, 10 g / L NaCl, and the pH value is 7; the trace mineral stock solution is 1.5 g / L nitrilotriacetic acid NTA, 0.1 g / L MnCl2·4H2O, 0.3 g / L FeSO4·7H2O, 0.17 g / L CoCl2·6H2O, 0.1 g / L ZnCl2, 0.04 g / L CuSO4·5H2O, 0.005 g / L KAl(SO4)2·12H2O, 0.005 g / L H3BO3, 0.09 g / L NaMoO4·2H2O, 0.12 g / L NiCl2·6H2O, 0.02 g / L NaWO4·2H2O, and 0.1 g / L NaSeO4.

[0048] Example 1

[0049] Figure 1 A process flow diagram for preparing the iron-reducing bacteria sulfidation modified zero-valent iron material of Example 1.

[0050] An iron-reducing bacteria sulfidation modified zero-valent iron material, the specific method being as follows:

[0051] Step one: sterilize the LB liquid medium at a temperature of 121°C for 20 min. Select the iron-reducing bacteria Shewanella strain, and cultivate it in 100 mL sterile LB liquid medium under aerobic conditions to obtain a Shewanella bacterial suspension, with a cultivation time of 17 h and a cultivation temperature of 35°C.

[0052] Step two: prepare the mineral salt liquid medium, with the following formula: 0.460 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.460 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, and 50 mM HEPES, with the pH value being adjusted to 7.2 using NaOH solution. Sterilize the mineral salt liquid medium at a temperature of 121°C for 20 min. Centrifuge the Shewanella at a speed of 4000 rpm for 10 min. Wash the Shewanella with sterile mineral salt liquid medium and re-disperse it into a Shewanella suspension.

[0053] Step three: in a sterile operation table, add 200 mL sterile mineral salt liquid medium to a 250 mL anaerobic bottle, and add the Shewanella suspension described in step two, with the final OD 600The value is 0.4, 20 mM sodium lactate is added as a carbon source, 5 mM sodium thiosulfate (Na2S2O3) is added as a sulfur source, and nitrogen gas is exposed for 30 min to remove dissolved oxygen in the medium.

[0054] Step four: 1 g of iron powder was added to the anaerobic bottle described in step three, sealed and placed in a shaker for 24 h to perform microbial sulfidation reaction, and the reaction temperature was 30℃.

[0055] Step five: Under an inert atmosphere, place the magnet at the bottom of the anaerobic bottle, separate the material from the solution by magnetism, then wash with deoxygenated water for 3 times, vacuum freeze-drying (-40℃ to -50℃, vacuum degree 5-10 Pa, 10-30 h) to obtain iron-reducing bacteria sulfidation modified zero-valent iron material.

[0056] Figure 2 The SEM and EDS images of the iron-reducing bacteria sulfidation modified zero-valent iron material prepared in Example 1 can be seen that the morphology of the iron-reducing bacteria sulfidation modified zero-valent iron is loose, irregular spherical structure, the particle size is nanoscale, and there are iron, oxygen, sulfur and carbon elements on the surface.

[0057] Figure 3 The S 2p XPS spectrum of the track, the main form of sulfur is S 2- , indicating that the iron-reducing bacteria successfully synthesized iron sulfide and realized sulfidation on the surface of zero-valent iron.

[0058] Example 2

[0059] An iron-reducing bacteria sulfidation modified zero-valent iron material, the specific method is as follows:

[0060] Step one: sterilize the LB liquid medium at a temperature of 121℃ for 20 min. Select iron-reducing bacteria Shewanella strain, cultivate in 100 mL sterile LB liquid medium under aerobic conditions to obtain Shewanella bacterial suspension, and the cultivation time is 17 h and the cultivation temperature is 35℃.

[0061] Step two: prepare mineral salt liquid medium, the formula is as follows: 0.460 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.460 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, 50 mM HEPES, adjust pH to 7.2 using NaOH solution. Autoclave the mineral salt liquid medium at 121℃ for 20 min. Centrifuge the Shewanella at 4000 rpm for 10 min. Wash the Shewanella with sterile mineral salt liquid medium and resuspend it into a Shewanella suspension.

[0062] Step three: add 200 mL of sterile mineral salt liquid medium to a 250 mL anaerobic flask in a sterile operation table, and add the Shewanella suspension described in step two, with a final OD value of 0.4, add 20 mM sodium lactate as a carbon source, add 5 mM sodium sulfite (Na2SO3) as a sulfur source, and expose to nitrogen gas for 30 min to remove dissolved oxygen in the medium. 600

[0063] Step four: add 1 g of iron powder to the anaerobic flask described in step three, seal it and place it in a shaker for 24 h to perform a microbial sulfidation reaction, with a reaction temperature of 30℃.

[0064] Step five: under an inert atmosphere, place a magnet at the bottom of the anaerobic flask, separate the material from the solution by magnetism, then wash it with deoxygenated water for 3 times, and vacuum freeze-dry to obtain the iron-reducing bacteria sulfidation-modified zero-valent iron material.

[0065] Example 3

[0066] An iron-reducing bacteria sulfidation-modified zero-valent iron material, the specific method is as follows:

[0067] Step one: autoclave the LB liquid medium at 121℃ for 20 min. Select the Shewanella strain, and culture it in 100 mL of sterile LB liquid medium under aerobic conditions to obtain a Shewanella bacterial suspension, with a culture time of 17 h and a culture temperature of 35℃.

[0068] ​Step 2: Prepare the mineral salt liquid culture medium with the following formula: 0.460 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.460 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, 50 mM HEPES. Adjust the pH to 7.2 using NaOH solution. Sterilize the mineral salt liquid culture medium at 121℃ for 20 min. Centrifuge to separate Shewanella bacteria at 4000 rpm for 10 min. Wash the Shewanella bacteria with sterile mineral salt liquid culture medium and redisperse them into a Shewanella suspension.

[0069] Step 3: In a sterile operating table, add 200 mL of sterile mineral salt liquid culture medium to a 250 mL anaerobic bottle, and then add the Shewanella suspension described in Step 2. The final OD... 600 The value was 0.4. 20 mM sodium lactate was added as a carbon source, and 10 mM sulfur powder (S) was added. 0 As a sulfur source, nitrogen gas was aerated for 30 minutes to remove dissolved oxygen from the culture medium.

[0070] Step 4: Add 1g of iron powder to the anaerobic bottle described in Step 3, seal it, place it in a shaker, and shake it thoroughly for 24 hours to carry out the microbial sulfidation reaction at a reaction temperature of 30℃.

[0071] Step 5: In an inert atmosphere, place a magnet at the bottom of the anaerobic bottle to separate the material from the solution through magnetic separation. Then wash three times with deoxygenated water and freeze-dry under vacuum to obtain zero-valent iron material modified by iron-reducing bacteria sulfidation.

[0072] Example 4

[0073] A zero-valent iron material modified by iron-reducing bacteria through sulfurization, the specific method is as follows:

[0074] Step 1: Sterilize LB liquid medium at 121℃ for 20 minutes. Select the iron-reducing bacterium Shewanella strain and incubate it in 100mL of sterile LB liquid medium under aerobic conditions to obtain a Shewanella bacterial suspension. Incubate for 17 hours at 35℃.

[0075] Step two: prepare mineral salt liquid medium, the formula is as follows: 0.460 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.460 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, 50 mM HEPES, adjust pH to 7.2 using NaOH solution. Autoclave the mineral salt liquid medium at 121℃ for 20 min. Centrifuge the Shewanella at 4000 rpm for 10 min. Wash the Shewanella with sterile mineral salt liquid medium and re-disperse into Shewanella suspension.

[0076] Step three: add 200 mL of sterile mineral salt liquid medium to a 250 mL anaerobic bottle in a sterile operation table, and add the Shewanella suspension described in step two, with a final OD value of 0.4, add 20 mM sodium lactate as a carbon source, add 5 mM sodium thiosulfate as a sulfur source, and expose to nitrogen for 30 min to remove dissolved oxygen in the medium. 600

[0077] Step four: add 1 g of iron powder to the anaerobic bottle described in step three, seal and place in a shaker, and fully shake for 6 h for microbial sulfidation reaction, with a reaction temperature of 30℃.

[0078] Step five: place a magnet at the bottom of the anaerobic bottle under an inert atmosphere, separate the material from the solution by magnetism, then wash with deoxygenated water for 3 times, and vacuum freeze-dry to obtain the iron-reducing bacteria sulfidation-modified zero-valent iron material.

[0079] Example 5

[0080] An iron-reducing bacteria sulfidation-modified zero-valent iron material, the specific method is as follows:

[0081] Step one: autoclave the LB liquid medium at 121℃ for 20 min. Select the Shewanella strain, and cultivate in 100 mL sterile LB liquid medium under aerobic conditions to obtain a Shewanella bacterial suspension, with a cultivation time of 17 h and a cultivation temperature of 35℃.

[0082] ​Step 2: Prepare the mineral salt liquid culture medium with the following formula: 0.460 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.460 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, 50 mM HEPES. Adjust the pH to 7.2 using NaOH solution. Sterilize the mineral salt liquid culture medium at 121℃ for 20 min. Centrifuge to separate Shewanella bacteria at 4000 rpm for 10 min. Wash the Shewanella bacteria with sterile mineral salt liquid culture medium and redisperse them into a Shewanella suspension.

[0083] Step 3: In a sterile operating table, add 200 mL of sterile mineral salt liquid culture medium to a 250 mL anaerobic bottle, and then add the Shewanella suspension described in Step 2. The final OD... 600 The value was 0.4. 20 mM sodium lactate was added as a carbon source and 5 mM sodium thiosulfate was added as a sulfur source. Nitrogen gas was aerated for 30 min to remove dissolved oxygen in the culture medium.

[0084] Step 4: Add 1g of iron powder to the anaerobic bottle described in Step 3, seal it, place it in a shaker, and shake it thoroughly for 12 hours to carry out the microbial sulfidation reaction at a reaction temperature of 30℃.

[0085] Step 5: In an inert atmosphere, place a magnet at the bottom of the anaerobic bottle to separate the material from the solution through magnetic separation. Then wash three times with deoxygenated water and freeze-dry under vacuum to obtain zero-valent iron material modified by iron-reducing bacteria sulfidation.

[0086] Example 6

[0087] A zero-valent iron material modified by iron-reducing bacteria through sulfurization, the specific method is as follows:

[0088] Step 1: Sterilize LB liquid medium at 121℃ for 20 minutes. Select the iron-reducing bacterium Shewanella strain and incubate it in 100mL of sterile LB liquid medium under aerobic conditions to obtain a Shewanella bacterial suspension. Incubate for 17 hours at 35℃.

[0089] Step two: prepare mineral salt liquid medium, the formula is as follows: 0.460 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.460 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, 50 mM HEPES, adjust pH to 7.2 using NaOH solution. Autoclave the mineral salt liquid medium at 121℃ for 20 min. Centrifuge the Shewanella at 4000 rpm for 10 min. Wash the Shewanella with sterile mineral salt liquid medium and re-disperse into Shewanella suspension.

[0090] Step three: add 200 mL of sterile mineral salt liquid medium to a 250 mL anaerobic bottle in a sterile operation table, and add the Shewanella suspension described in step two, with a final OD 600 value of 0.4, add 20 mM sodium lactate as a carbon source, add 5 mM sodium thiosulfate as a sulfur source, and expose to nitrogen gas for 30 min to remove dissolved oxygen in the medium.

[0091] Step four: add 1 g of iron powder to the anaerobic bottle described in step three, seal and place in a shaker for 18 h of microbial sulfidation reaction at 30℃.

[0092] Step five: under an inert atmosphere, place a magnet at the bottom of the anaerobic bottle, separate the material from the solution by magnetism, then wash with deoxygenated water for 3 times, and vacuum freeze-dry to obtain the iron-reducing bacteria sulfidation-modified zero-valent iron material.

[0093] Example 7

[0094] An iron-reducing bacteria sulfidation-modified zero-valent iron material, the specific method is as follows:

[0095] Step one: autoclave the LB liquid medium at 121℃ for 20 min. Select the Shewanella strain, and culture in 100 mL sterile LB liquid medium under aerobic conditions to obtain a Shewanella bacterial suspension, with a culture time of 17 h and a culture temperature of 35℃.

[0096] Step two: prepare mineral salt liquid medium, the formula is as follows: 0.460 g / L NaCl, 0.225 g / L (NH4)2SO4, 0.225 g / L KH2PO4, 0.225 g / L K2HPO4, 0.460 g / L MgSO4·7H2O, 10 mL / L trace mineral stock solution, 50 mM HEPES, adjust pH to 7.2 using NaOH solution. Autoclave the mineral salt liquid medium at 121 °C for 20 min. Centrifuge Shewanella at 4000 rpm for 10 min. Wash the Shewanella with sterile mineral salt liquid medium and re-disperse into Shewanella suspension.

[0097] Step three: add 200 mL sterile mineral salt liquid medium into 250 mL anaerobic flask in a sterile operation table, and add the Shewanella suspension described in step two, with final OD value of 0.4, add 20 mM sodium lactate as carbon source, add 5 mM sodium thiosulfate as sulfur source, and expose to nitrogen gas for 30 min to remove dissolved oxygen in the medium. 600

[0098] Step four: add 1 g iron powder into the anaerobic flask described in step three, seal and place in a shaker for 30 h of microbial sulfidation reaction at 30 °C.

[0099] Step five: under inert atmosphere, place a magnet at the bottom of the anaerobic flask, separate the material from the solution by magnetism, then wash 3 times with deoxygenated water, and vacuum freeze-dry to obtain the iron-reducing bacteria sulfidation-modified zero-valent iron material.

[0100] Application Example 1

[0101] Removal of halogenated organic pollutants: add 50 mL of 10 ppm tetrabromobisphenol A solution into a 100 mL conical flask, adjust the pH of the solution to 7.0 using HCl and NaOH, respectively, add 0.1 g of the iron-reducing bacteria sulfidation-modified zero-valent iron material (BS-ZVI) prepared in Examples 1-3, and place in a shaker under aerobic conditions at 160 rpm and 25 °C. Take samples at regular intervals and measure the concentration of tetrabromobisphenol A in the system (high performance liquid chromatography, mobile phase 70% acetonitrile + 30% water, flow rate 1.0 mL / min, column temperature 30 °C, UV detector wavelength 273 nm). As a control experiment, 0.1 g of iron powder (ZVI) is added to the tetrabromobisphenol A solution, and other conditions remain unchanged.

[0102] The experimental results are shown in Table 1. Figure 3 Figure 3 ​​As can be seen, depending on the sulfur source added, the zero-valent iron material modified by sulfurization with iron-reducing bacteria of the present invention achieved removal rates of 66%, 89%, and 100% for tetrabromobisphenol A within 65 hours, respectively; while the removal rate of iron powder for tetrabromobisphenol A was only 6%, showing almost no removal effect. The above fully demonstrates that the zero-valent iron material modified by sulfurization with iron-reducing bacteria prepared in this invention can significantly enhance the reactivity of zero-valent iron, achieving highly efficient removal of tetrabromobisphenol A.

[0103] Application Example 2

[0104] Heavy metal removal: 50 mL of a 10 ppm hexavalent chromium solution was added to a 100 mL Erlenmeyer flask. The pH of the solution was adjusted to 7.0 using HCl and NaOH. 0.1 g of the iron-reducing bacteria-modified zero-valent iron material (BS-ZVI) prepared in Examples 1-3 was added. The flask was placed in an aerobic environment and shaken at 160 rpm and 25 °C. Samples were taken at regular intervals to determine the concentration of hexavalent chromium in the system (using the diphenylcarbazide spectrophotometric method, UV-Vis absorption spectrometer, wavelength 540 nm). As a control, 0.1 g of iron powder (ZVI) was added to the hexavalent chromium solution, with other conditions unchanged.

[0105] Experimental results are as follows Figure 4 As shown. From Figure 4 As can be seen, depending on the sulfur source added, the zero-valent iron material modified by iron-reducing bacteria of the present invention achieved removal rates of 86%, 91%, and 100% for hexavalent chromium within 60 minutes; while the removal rate of hexavalent chromium by iron powder was only 13%. This fully demonstrates that the zero-valent iron material modified by iron-reducing bacteria prepared by the present invention can significantly enhance the reactivity of zero-valent iron, achieving highly efficient removal of hexavalent chromium.

[0106] Application Example 3

[0107] Removal of halogenated organic pollutants: 50 mL of a 10 ppm tetrabromobisphenol A solution was added to a 100 mL Erlenmeyer flask. The pH of the solution was adjusted to 7.0 using HCl and NaOH. 0.1 g of the iron-reducing bacteria-modified zero-valent iron material prepared in Examples 4-7 was added. The flask was placed in an aerobic environment and shaken at 160 rpm and 25 °C. Samples were taken at regular intervals to determine the concentration of tetrabromobisphenol A in the system. As a control, 0.1 g of iron powder was added to the tetrabromobisphenol A solution, with other conditions remaining unchanged.

[0108] The experimental results are shown in Table 1. According to different iron-reducing bacteria sulfuration reaction times, the removal rates of the iron-reducing bacteria sulfuration modified zero-valent iron material of the present application to tetrabromobisphenol are 62%, 89%, 97% and 100% within 65 h; while the removal rate of iron powder to tetrabromobisphenol is only 7%, almost no removal effect. The above fully shows that the iron-reducing bacteria sulfuration modified zero-valent iron material prepared by the present application can significantly improve the reaction activity of zero-valent iron, and within a certain time range, the reaction performance gradually increases with the extension of the iron-reducing bacteria sulfuration reaction time, thereby realizing efficient removal of tetrabromobisphenol A.

[0109] Application Example 4

[0110] Removal of heavy metals: 50 mL of a hexavalent chromium solution with a concentration of 10 ppm is added to a 100 mL conical flask, HCl and NaOH are used to adjust the pH of the solution to 7.0, 0.1 g of the iron-reducing bacteria sulfuration modified zero-valent iron material prepared in Examples 4-7 is added, and the system is placed in a shaking table under aerobic conditions, with a rotation speed of 160 rpm and a temperature of 25°C. Samples are taken at intervals, and the concentration of hexavalent chromium in the system is determined. As a control experiment, 0.1 g of iron powder is added to the hexavalent chromium solution, and other conditions remain unchanged.

[0111] The experimental results are shown in Table 2. According to different iron-reducing bacteria sulfuration reaction times, the removal rates of the iron-reducing bacteria sulfuration modified zero-valent iron material of the present application to hexavalent chromium are 43%, 87%, 100% and 100% within 60 min; while the removal rate of iron powder to hexavalent chromium is only 13%. The above fully shows that the iron-reducing bacteria sulfuration modified zero-valent iron material prepared by the present application can significantly improve the reaction activity of zero-valent iron, and within a certain time range, the reaction performance gradually increases with the extension of the iron-reducing bacteria sulfuration reaction time, thereby realizing efficient removal of hexavalent chromium.

[0112] Application Example 5

[0113] Removal of halogenated organic pollutants: 50 mL of a tetrabromobisphenol A solution with a concentration of 10 ppm is added to a 100 mL conical flask, HCl and NaOH are used to adjust the pH of the solution to 3.0, 0.1 g of the iron-reducing bacteria sulfuration modified zero-valent iron material prepared in Example 1 is added, and the system is placed in a shaking table under aerobic conditions, with a rotation speed of 160 rpm and a temperature of 25°C. Samples are taken at intervals, and the concentration of tetrabromobisphenol A in the system is determined.

[0114] The experimental results are shown in Table 1. The removal rate of the iron-reducing bacteria sulfuration modified zero-valent iron material of the present application to tetrabromobisphenol A is 100% within 36 h. The above fully shows that the iron-reducing bacteria sulfuration modified zero-valent iron material prepared by the present application can realize efficient removal of tetrabromobisphenol A in an acidic environment.

[0115] Application Example 6

[0116] Removal of heavy metals: 50 mL of hexavalent chromium solution with a concentration of 10 ppm was added into a 100 mL conical flask, the pH of the solution was adjusted to 3.0 by using HCl and NaOH, 0.1 g of the iron-reducing bacteria sulfidation-modified zero-valent iron material prepared in Example 1 was added, and the system was placed in a shaking table for oscillation under aerobic conditions at a speed of 160 rpm and a temperature of 25°C. Samples were taken at intervals, and the concentration of hexavalent chromium in the system was determined.

[0117] The experimental results are shown in Table 2. The removal rate of the iron-reducing bacteria sulfidation-modified zero-valent iron material of the present application for hexavalent chromium was 100% within 20 min. This fully demonstrates that the iron-reducing bacteria sulfidation-modified zero-valent iron material prepared in the present application can achieve efficient removal of hexavalent chromium in an acidic environment.

[0118] Application Example 7

[0119] Removal of halogenated organic pollutants: 50 mL of tetrabromobisphenol A solution with a concentration of 10 ppm was added into a 100 mL conical flask, the pH of the solution was adjusted to 9.0 by using HCl and NaOH, 0.1 g of the iron-reducing bacteria sulfidation-modified zero-valent iron material prepared in Example 1 was added, and the system was placed in a shaking table for oscillation under aerobic conditions at a speed of 160 rpm and a temperature of 25°C. Samples were taken at intervals, and the concentration of tetrabromobisphenol A in the system was determined.

[0120] The experimental results are shown in Table 1. The removal rate of the iron-reducing bacteria sulfidation-modified zero-valent iron material of the present application for tetrabromobisphenol A was 71% within 65 h. This fully demonstrates that the iron-reducing bacteria sulfidation-modified zero-valent iron material prepared in the present application can achieve efficient removal of tetrabromobisphenol A in an alkaline environment.

[0121] Application Example 8

[0122] Removal of heavy metals: 50 mL of hexavalent chromium solution with a concentration of 10 ppm was added into a 100 mL conical flask, the pH of the solution was adjusted to 9.0 by using HCl and NaOH, 0.1 g of the iron-reducing bacteria sulfidation-modified zero-valent iron material prepared in Example 1 was added, and the system was placed in a shaking table for oscillation under aerobic conditions at a speed of 160 rpm and a temperature of 25°C. Samples were taken at intervals, and the concentration of hexavalent chromium in the system was determined.

[0123] The experimental results are shown in Table 2. The removal rate of the iron-reducing bacteria sulfidation-modified zero-valent iron material of the present application for hexavalent chromium was 100% within 60 min. This fully demonstrates that the iron-reducing bacteria sulfidation-modified zero-valent iron material prepared in the present application can achieve efficient removal of hexavalent chromium in an alkaline environment.

[0124] The experimental results are summarized in the following tables. Compared with the raw iron powder, the iron-reducing bacteria sulfidation modified zero-valent iron material prepared by the present application has better removal effect on halogenated organic pollutants and heavy metals in water. The iron-reducing bacteria sulfidation modified zero-valent iron material synthesized by the present application has significantly improved reduction capacity for pollutants, and the synthesis method is green and safe, environmentally friendly, and has a wide range of sulfidation time in the preparation process, and can be applied to different acid-base environments in the process of removing pollutants. The iron-reducing bacteria sulfidation modified zero-valent iron material can efficiently reduce and remove various halogenated organic compounds and heavy metals and other pollutants in water, and has broad practical application potential in wastewater treatment.

[0125] Table 1 Removal of tetrabromobisphenol A in each case

[0126]

[0127]

[0128] Table 2 Removal of hexavalent chromium in each case

[0129] Example / Application Example Degradation time / min Removal rate / % Blank group 60 13 Example 1 / Application Example 2 30 100 Example 2 / Application Example 2 60 91 Example 3 / Application Example 2 60 86 Example 4 / Application Example 4 60 43 Example 5 / Application Example 4 60 87 Example 6 / Application Example 4 30 100 Example 7 / Application Example 4 30 100 Example 1 / Application Example 6 20 100 Example 1 / Application Example 8 60 100

[0130] The preferred embodiments of the present application disclosed above are only used to help illustrate the present application, but the present application is not limited thereto. It can be understood by those skilled in the art that within the technical concept of the present application, the technical solutions of the present application can be modified, or some technical features can be combined in any other way, and these modifications or combinations do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be considered as the disclosed content of the present application, and all belong to the protection scope of the present application.

Claims

1. A method for preparing a sulfur-modified zero-valent iron material of iron-reducing bacteria, characterized by, The method comprises the following steps: The Shewanella bacterial suspension, mineral salt liquid medium, carbon source, sulfur source and iron powder are mixed to carry out a microbial sulfuration reaction under anaerobic conditions, so as to obtain the iron-reducing bacteria sulfuration modified zero-valent iron material; The carbon source is selected from sodium lactate; The sulfur source is selected from one or more of sodium thiosulfate, sodium sulfite and sulfur powder; The concentration of the carbon source in the reaction system of the microbial sulfuration reaction is 10-40 mmol / L; The concentration of the sulfur source in the reaction system of the microbial sulfuration reaction is 2-20 mmol / L; The iron-reducing bacteria sulfuration modified zero-valent iron material takes zero-valent iron as the core; the surface of the zero-valent iron is wrapped with iron-sulfur oxide and microbial extracellular polymer.

2. The production method according to claim 1, characterized by, The Shewanella bacterial suspension is prepared by the following method: After the Shewanella strain is cultured in the LB liquid medium, centrifugal separation is carried out, and the dispersed Shewanella bacterial suspension is obtained by washing with the mineral salt liquid medium.

3. The preparation method according to claim 2, characterized in that, The culture temperature is 30-35 DEG C; the culture time is 16-24 h; the centrifugal separation speed is 3000-5000 rpm; and the centrifugal separation time is 10-15 min.

4. The method of claim 1, wherein, OD of Shewanella suspensions mixed with mineral salt liquid medium 600 was 0.2 to 0.5; The concentration of the iron powder in the reaction system of the microbial sulfuration reaction is 4-8 g / L.

5. The preparation method according to claim 1, characterized in that, The mineral salt liquid medium comprises 0.4-0.5 g / L NaCl, 0.2-0.3 g / L (NH4)2SO4, 0.2-0.3 g / L KH2PO4, 0.2-0.3 g / L K2HPO4, 0.4-0.5 g / L MgSO4•7H2O, 8-12 mL / L trace mineral stock solution and 40-60 mM HEPES buffer, and the pH is adjusted to 6.9-7.4 by using NaOH solution.

6. The method of claim 1, wherein, The temperature of the microbial sulfuration reaction is 30-35 DEG C; and the time of the microbial sulfuration reaction is 6-40 h. 7.The iron-reducing bacteria sulfuration modified zero-valent iron material prepared by the preparation method of any one of claims 1-6, wherein the iron-reducing bacteria sulfuration modified zero-valent iron material takes zero-valent iron as the core; and the surface of the zero-valent iron is wrapped with iron-sulfur oxide and microbial extracellular polymer. 8.The application of the iron-reducing bacteria sulfuration modified zero-valent iron material prepared by the preparation method of any one of claims 1-6 or the iron-reducing bacteria sulfuration modified zero-valent iron material of claim 7 in wastewater treatment.

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