CN115960971A - Bimetallic iron-nickel sulfide nano composite material and preparation method and application thereof - Google Patents

Abstract

The invention discloses a bimetallic iron-nickel sulfide nano composite material and a preparation method and application thereof, wherein the preparation method comprises the following steps: under the anaerobic condition, carrying out shake culture on sulfate reducing bacteria in a culture solution containing water-soluble ferric salt, water-soluble nickel salt and water-soluble sulfur-containing compounds to obtain the NiFeS nano composite material. The invention uses sulfate reducing bacteria to take organic matters as metabolic substrates, takes sulfate as an electron acceptor after generating electrons, and combines hydrogen sulfide generated by biological reduction of sulfate with additional metal ions to form the bimetallic iron-nickel sulfide nano composite material. Therefore, the method can be used for green and efficient recovery of heavy metals in the actual electroplating wastewater and rapid synthesis of high-performance electrocatalysts, and has good application prospects in heavy metal wastewater treatment, nano material green synthesis and renewable energy production.

Description

Bimetallic iron-nickel sulfide nano composite material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of wastewater treatment and biosynthesis of nano materials, and particularly relates to a bimetallic iron-nickel sulfide (NiFeS) nano composite material as well as a preparation method and application thereof.

Background

Hydrogen is an ideal clean energy source and is expected to replace the traditional fossil fuel. The hydrogen production by water electrolysis is an important development direction at present, and renewable energy sources such as solar energy, wind energy, geothermal energy and the like can be used for driving the cathode to electrolyze water to produce hydrogen, so that the effective storage of unstable energy is realized. In addition, the CO can be further reduced by a cathode ₂ Realizing carbon conversion and generating chemicals with higher added value. However, the corresponding anodic reaction (typically oxygen evolution reaction, OER) is generally slow and thus becomes the rate-limiting step for the overall electrochemical reaction.

Although the ruthenium-based and iridium-based noble metal nano-catalysts commonly used at present have excellent activity, the scarcity and high cost thereof seriously hinder the large-scale application of the catalysts. Therefore, there is a need to develop an OER catalyst that is inexpensive and has high electrocatalytic activity and stability. In this respect, bimetallic iron-nickel sulfide (NiFeS) has catalytic activity comparable to that of noble metal materials, and is abundant in source and low in cost. However, the preparation of the NiFeS catalyst usually requires a complex hydrothermal method, a thermal solution method and a stripping method, and not only the preparation conditions are severe, but also secondary pollution (such as generation of toxic organic cleaning solution) and safety risk (such as leakage of toxic gas hydrogen sulfide) exist.

One possible alternative approach is to use living microorganisms to synthesize the metal sulfide nano material, and compared with the traditional physical and chemical method, the biological synthesis method has the advantages of simple operation, environmental friendliness, lower cost and the like. At present, people successfully obtain a plurality of sulfide nano materials by utilizing a biosynthesis method, but the synthesis is only limited to single metal sulfides, and the synthesis of bimetallic sulfides by utilizing microorganisms is not reported at present. In addition, the existing method generally adopts thiosulfate as a sulfur source to react with additional metal salt to realize the biosynthesis of the metal sulfide, and no report exists for synthesizing the metal sulfide by directly utilizing sulfate and metal ions in wastewater to carry out biotransformation. If the process can be realized, a new way is provided for recycling the nickel-containing wastewater, and the problems of wastewater treatment and low-cost preparation of the nickel-containing electrode material are solved. Finally, the existing biosynthetic metal sulfide nano material is mainly used for improving the power generation efficiency of a microbial electrochemical system and promoting the degradation and conversion of toxic pollutants, and no report of the application of the existing biosynthetic metal sulfide nano material in OER exists.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a bimetallic iron-nickel sulfide (NiFeS) nano composite material and a preparation method and application thereof. Therefore, the invention provides a new method for recovering heavy metals in the actual electroplating wastewater and realizing value-added conversion and resource utilization of the heavy metals, and the method has good application prospects in the fields of heavy metal wastewater treatment, nano-material green synthesis and renewable energy production.

The technical scheme of the invention is as follows:

the invention relates to a preparation method of a bimetallic iron-nickel sulfide nano composite material, which comprises the following steps:

s1, under the anaerobic condition, carrying out shake culture on sulfate reducing bacteria in a culture solution containing water-soluble ferric salt, water-soluble divalent nickel salt and a water-soluble sulfur-containing compound to obtain the NiFeS nano composite material.

The invention mainly utilizes sulfate reducing bacteria, takes organic matters as metabolic substrates, takes sulfate as an electron acceptor after generating electrons, and generates hydrogen sulfide (H) by biological reduction of sulfate ₂ S) and added metal ions (Fe) ³⁺ 、Ni ²⁺ ) Combine to form binary metal sulfide nanoparticles (NiFeS). Since sulfides generated by biological reduction of sulfate radicals can be directly combined with metal ions in the actual wastewater rapidly and generate metal sulfide precipitates, the preparation method can also be used for recovering heavy metals from the actual electroplating wastewater.

Preferably, the sulfate-reducing bacteria is one or more of vibrio desulfovii, pseudomonas desulfonidis, phyllobacterium desulforum and enterobacter desulforum. And further preferably Vibrio vulgaris (D.vulgaris Hildenborough), and compared with other strains, the Vibrio vulgaris has the advantages of mature culture process, clear genetic background, wide existence range, strong environmental adaptability and the like.

Preferably, the water-soluble ferric salt is one or more of ferric chloride, ferric sulfate, ferric ammonium sulfate and ferric citrate;

the water-soluble divalent nickel salt is one or more of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate and nickel citrate;

the water-soluble sulfur-containing compound is one or more of thiosulfate, sulfate, sulfite and sulfide.

Preferably, step S1 comprises the steps of:

s11, dispersing sulfate reducing bacteria in the culture solution after deoxygenation and sterilization to obtain a bacterial solution;

and S12, adding water-soluble ferric salt, water-soluble nickel salt and water-soluble sulfur-containing compound into the bacterial liquid under an anaerobic condition to obtain a culture system, and performing shaking culture to obtain the NiFeS nano composite material.

Preferably, OD of the bacterial liquid obtained in step (1) ₆₀₀ 0.1 to 3;

the concentration of the ferric iron salt in the culture system in the step (2) is 0.1-10 mmol/L, the concentration of the divalent nickel salt is 0.1-10 mmol/L, and the concentration of the water-soluble sulfur-containing compound is 0.1-10 mmol/L; wherein the molar ratio of iron to nickel elements is 1: (0.1-10).

Preferably, the temperature of the shaking culture is 4-50 ℃, the rotating speed is 200rpm, and the time is 24-72 h.

Preferably, the method further comprises the following steps:

s2, centrifuging a product obtained after the shaking culture to collect sediments containing somatic cells and black particles, then cleaning, and drying the obtained material;

and S3, carrying out heat treatment on the product obtained in the step S2, raising the temperature to 100-500 ℃ at a heating rate of 1-10 ℃/min in an argon atmosphere, and keeping the temperature for 0.5-5 h.

The invention also relates to the application of the preparation method in wastewater treatment, wherein the wastewater contains Ni ²⁺ 、Fe ³⁺ And a water-soluble sulfur-containing compound. For example, using chemical rich nickel (Ni) ²⁺ ) And Sulfates (SO) ₄ ^2- ) The actual electroplating wastewater is used as a nickel source and a sulfur source, the wastewater is treated by additionally adding ferrous iron salt, and meanwhile, the NiFeS nano composite material can be biosynthesized.

The invention also relates to a bimetallic iron-nickel sulfide nano composite material prepared by the preparation method.

The invention also relates to the application of the bimetallic iron-nickel sulfide nanocomposite material in electrocatalytic reaction, wherein the electrocatalytic application comprises one or more reactions of electrocatalytic Oxygen Evolution (OER), hydrogen Evolution (HER) and oxygen reduction (ORR).

The beneficial effects of the invention are:

(1) The invention utilizes sulfate reducing bacteria to take organic matters as metabolic substrates, takes sulfate as an electron acceptor after generating electrons, and generates hydrogen sulfide (H) by biological reduction of sulfate ₂ S), the latter with metal ions (Fe) ³⁺ 、Ni ²⁺ ) Combining to form a bimetallic iron-nickel sulfide nano composite material (NiFeS); compared with the traditional physicochemical method with severe synthesis conditions, complex operation process and potential environmental hazardThe method is simple and easy to operate, low in cost, green and environment-friendly, and has attractive force and application prospect.

(2) The bacterial cells combine with metal ions to form metal sulfide nano-particles based on sulfides generated by self metabolism, and the obtained metal sulfide nano-materials are uniformly dispersed under the action of extracellular organic matters such as protein and polysaccharide, so that the aggregation of the nano-particles can be effectively prevented to a certain extent, and the high dispersibility and high catalytic activity of the nano-particles in subsequent electrocatalysis application are ensured.

(3) In addition, sulfide generated by biological reduction of sulfate radicals can be rapidly and directly combined with metal ions in actual wastewater to generate metal sulfide precipitate, so that fatal poison of heavy metals to microorganisms can be effectively avoided, valuable heavy metals can be recovered from actual electroplating wastewater and used for synthesizing high-performance electrocatalysts, and the application of the biological synthesis nano-material technology in the fields of heavy metal wastewater treatment, resource recovery and renewable energy production is further widened.

Drawings

The invention is further described below with reference to the following figures and examples:

FIG. 1 is a TEM (FIG. 1A) and HRTEM (FIG. 1B) spectra of product 1 obtained in example 1 of the present invention;

FIG. 2 is an XRD pattern of product 1 obtained in example 1 of the present invention;

FIG. 3 is an XPS spectrum of product 1 obtained in example 1 of the present invention;

FIG. 4 shows the LSV polarization curve, EIS curve and stability curve of the product 1 obtained in example 1 of the present invention;

FIG. 5 is an XRD spectrum and XPS spectrum of product 7 obtained in example 7 of the present invention;

FIG. 6 shows the LSV polarization curve, EIS curve and stability curve of the product 7 obtained in example 7 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

The invention provides a preparation method of a NiFeS nano composite material, which comprises the following steps: (1) Dispersing sulfate reducing bacteria in the culture solution after deoxidization and sterilization to obtain a bacterial solution; (2) Under the anaerobic condition, adding water-soluble ferric salt, water-soluble divalent nickel salt and water-soluble sulfur-containing compound into the bacterial liquid to obtain a culture system, and performing shaking culture to obtain the NiFeS nano composite material. The NiFeS nano composite electrocatalyst with the best electrocatalytic performance is screened out by optimizing the adding ratio of metal Fe and Ni, changing the heat treatment temperature of the biosynthetic catalyst and combining with an electrochemical characterization means.

In the present invention, the sources of all raw materials are not particularly limited, and they may be commercially available.

Wherein the sulfate reducing bacteria is selected from one or more of vibrio desulfovii, pseudomonas desulfurativa, phyllobacterium desulfurativa and enterobacter desulfurativa, and vibrio desulfovibrio is further preferred. In the present invention, the sulfate-reducing bacteria are preferably obtained by culturing a strain of sulfate-reducing bacteria; the culture method is known to those skilled in the art, and is not limited in any way, and takes the vibrio desulfovibrio vulgaris as an example, the vibrio desulfovibrio vulgaris strain is inoculated into a liquid culture medium and is statically cultured at a constant temperature to complete strain activation; then transferring the strain to a fresh culture medium according to the same proportion, and culturing under the same condition to complete strain amplification. The temperature of the static culture is preferably 4-50 ℃, more preferably 10-40 ℃, further preferably 20-35 ℃, and most preferably 30 ℃; the time of static culture is preferably 24 to 72 hours, more preferably 36 to 60 hours, and still more preferably 48 hours; the volume ratio of the suspension to the liquid medium is preferably 1: (80 to 120), more preferably 1:100; the activation is preferably carried out under the same culture conditions; the activation time is preferably 24 to 72 hours, more preferably 36 to 60 hours, and still more preferably 48 hours.

Taking desulfovibrio as an example, the desulfovibrio is dispersed in the culture solution after the deoxidization and sterilization treatment,obtaining a bacterial liquid; OD of the bacterial liquid ₆₀₀ Namely OD of desulfurization vibrio in culture solution ₆₀₀ Preferably 0.1 to 3, more preferably 0.3 to 2, still more preferably 0.3 to 1, and most preferably 0.3 to 0.5.

The culture solution is preferably a mineral salt culture solution; the mineral salt culture medium solution preferably comprises 5 to 20g of HEPES, 0.1 to 3g/L of sodium sulfate, 1 to 5g/L of sodium chloride, 1 to 5g/L of ammonium chloride, 0.1 to 0.5g/L of calcium chloride dihydrate, 0.1 to 0.5g/L of magnesium chloride hexahydrate, 0.01 to 0.5g/L of yeast extract, 1 to 5mL of 60% sodium lactate solution and 1 to 20mL of trace element mother solution, more preferably comprises 5 to 15g of HEPES, 0.1 to 1g/L of sodium sulfate, 1 to 3g/L of sodium chloride, 1 to 3g/L of ammonium chloride, 0.1 to 0.3g/L of calcium chloride dihydrate, 0.2 to 0.4g/L of magnesium chloride hexahydrate, 0.05 to 0.2 of yeast extract, 1 to 3mL of 60% sodium lactate solution, 5 to 15mL of trace element mother solution, most preferably 10 to 15g/L of HEPES, 0.5 to 1g/L of sodium sulfate, 1 to 3g/L of sodium chloride, 0.1 to 2g/L of sodium lactate, 0.1 to 3L of yeast extract, 0.8 to 3mL of magnesium chloride hexahydrate solution and 0.8 to 3mL of trace element mother solution; the pH value of the culture solution is preferably 6.5-7.5, and more preferably 7.0; the culture solution is preferably deoxygenated by aeration with nitrogen; the time for nitrogen exposure is preferably 20-30 min; the sterilization conditions are preferably 121 ℃ and 20min.

And under an anaerobic condition, adding water-soluble ferric salt, divalent nickel salt and a water-soluble sulfur-containing compound into the bacterial liquid to obtain a culture system, and performing shaking culture to obtain the NiFeS nano composite material. Wherein the water-soluble ferric salt is preferably one or more of ferric chloride, ferric sulfate, ferric ammonium sulfate and ferric citrate; the water-soluble divalent nickel salt is preferably one or more of nickel chloride, nickel sulfate, nickel nitrate and nickel citrate; the water-soluble sulfur-containing compound is preferably one or more of thiosulfate, sulfite and sulfide; the cations in the thiosulphate, sulphite and sulphide salts are preferably sodium and/or potassium ions. The concentration of the water-soluble ferric salt in the culture system is preferably 0.1-10 mmol/L, more preferably 0.1-7 mmol/L, still more preferably 0.1-5 mmol/L, still more preferably 0.1-3 mmol/L, and most preferably 0.3-1.5 mmol/L; the concentration of the water-soluble divalent nickel salt is preferably 0.1 to 10mmol/L, more preferably 0.1 to 7mmol/L, still more preferably 0.1 to 3mmol/L, and most preferably 1 to 2.5mmol/L; the initial iron-nickel element concentration ratio is preferably 1: (0.1 to 10), more preferably 1: (0.5 to 10), most preferably 1: (1-10); the concentration of the water-soluble sulfur-containing compound in the culture solution containing the water-soluble ferric salt and the water-soluble sulfur-containing compound is preferably 0.1 to 10mmol/L, more preferably 0.1 to 5mmol/L, more preferably 0.1 to 3mmol/L, and more preferably 0.1 to 1mmol/L; the temperature of the shaking culture is preferably 4-50 ℃, more preferably 10-40 ℃, further preferably 20-35 ℃ and most preferably 30 ℃; the period of shaking culture is preferably 24 to 72 hours, more preferably 36 to 60 hours, and still more preferably 48 hours.

After shaking culture, the sediment containing the somatic cells and black particles was collected by centrifugation, washed twice (10000 g, 5-10 min) with ultrapure water, and the resulting material was dried in a vacuum freeze-dryer for 12-48 h.

After drying treatment, taking the NiFeS nano composite material prepared by a biological method as a precursor, heating to 100-500 ℃ at a heating rate of 1-10 ℃/min in an argon atmosphere, and preserving heat for 0.5-5 hours. The heat treatment can further enhance the crystallinity of the biosynthetic nano material complex and improve the conductivity of the material, thereby obtaining the NiFeS material with higher electrocatalytic activity.

The invention also provides the application of the preparation method in wastewater treatment, wherein the wastewater contains Ni ²⁺ 、Fe ³⁺ And a water-soluble sulfur-containing compound.

The invention also provides application of the NiFeS nano composite material prepared by the preparation method in an electro-catalysis system.

The electrocatalytic application includes electrocatalytic one or more of Oxygen Evolution (OER), hydrogen Evolution (HER), and oxygen reduction (ORR) reactions. In the examples provided herein, the electrocatalytic application is an electrocatalytic Oxygen Evolution Reaction (OER).

According to the invention, the method for testing the electrocatalysis performance comprises the following steps: (1) preparation of an electrode: weighing 4mg of the pretreated catalyst and 1mg of acetylene black, and placing the catalyst and the acetylene black into a 1.5mL centrifuge tube; in turn add490. Mu.L of ultrapure water, an equal volume of isopropanol (hydroalcoholic volume ratio of 1) and 20. Mu.L of Nafion solution; and (4) performing ultrasonic treatment for half an hour to obtain a homogeneous suspension of the catalyst and acetylene black mixture. Then, 10. Mu.L of the suspension was uniformly applied dropwise to the surface of a polished glassy carbon electrode having a diameter of 5 mm. (2) oxygen evolution reaction test: all electrochemical tests were performed in a single component three-electrode format and the test data were collected at the CHI760E electrochemical workstation. An Ag/AgCl (3M KCl) electrode and a platinum wire are respectively used as a reference electrode and a counter electrode, and a 1.0M KOH solution is used as an electrolyte. The test range of the polarization curve is 1.3-1.8V vs. RHE, and the sweep rate is 5mV s ^-1 Fully stirring the solution by using a magnetic stirrer in the test process; (3) Electrochemical Impedance Spectroscopy (EIS) test: the electrolyte is 1.0M KOH solution, the initial electrode potential is respectively the current density in the LSV curve of each catalyst is 10mA cm ^-1 At a corresponding electrode potential, the amplitude was fixed at 5mV and the frequency range was set at 100kHz to 0.1Hz. When the catalyst stability test was performed, the current-time curve of the electrocatalyst at a fixed electrode potential (1.5V vs RHE) was determined.

The NiFeS nano composite material prepared by the invention takes sulfate reducing bacteria as a cell factory for the first time, takes sulfate radical and heavy metal ions in wastewater as precursors, realizes the successful biosynthesis of the bimetal sulfide NiFeS and is applied to electrocatalytic decomposition of water; the biosynthesized bimetallic sulfide NiFeS can provide a large number of active sites for electrocatalytic reduction water, and good dispersibility and conductivity are key factors for ensuring high electrocatalytic activity of the water. The easy operability, high efficiency and stability of the invention embody strong practical application potential in the fields of heavy metal wastewater treatment, resource recovery and renewable energy production.

Example 1

Selecting typical common vibrio desulfurizati D.vulgaris Hildenborough to carry out biosynthesis of the NiFeS nanocomposite, and carrying out heat treatment, material characterization and performance test on the obtained NiFeS nanocomposite.

(1) Preparation of a culture medium: to 800mL of deionized water were added 11.91g of HEPES,0.71g of Na in this order ₂ SO ₄ ，2.675g NH ₄ Cl，1.7g NaCl，0.26g CaC1 ₂ ·2H ₂ O，0.34g MgCl ₂ ·6H ₂ O,0.1g yeast extract, 2.79mL60% sodium lactate solution and 10mL microelement mother liquor. After all the medicines are completely dissolved and mixed uniformly, the pH value of the medicine is adjusted to 7.0 by using a KOH (4M) solution, and deionized water is supplemented to 1000mL and is fully mixed. Then the solution with the same volume (100 mL) is subpackaged into a 125mL serum bottle, and high-purity N is introduced ₂ Aerating for 30min, sealing with butyl rubber stopper and aluminum cap, and high pressure steam sterilizing (121 deg.C, 20 min).

(2) Culturing vibrio desulfurizate: taking out a small amount of bacterial liquid from a strain freezing tube stored in an ultra-low temperature refrigerator at minus 80 ℃, inoculating the bacterial liquid to the prepared liquid culture medium according to the inoculation proportion of 1% (v/v), and placing the bacterial liquid in a constant temperature incubator at 30 ℃ for standing culture for 48h to complete bacterial strain activation; then transferring the strain into a fresh culture medium according to the same proportion, and culturing for 48 hours under the same condition to complete strain amplification.

(3) Biosynthesis of the NiFeS nanocomposite: subjecting the above activated strain to amplification culture for 48 hr, centrifuging to collect thallus (6000g, 10min), cleaning twice with mineral salt culture medium with oxygen-removing sterilization in anaerobic condition, sucking a certain volume of bacteria suspension, injecting into a serum bottle containing 100mL fresh mineral salt culture medium, and controlling initial inoculation density of bacteria to OD ₆₀₀ =0.4. Then, a ferric chloride mother liquor (FeCl) was injected into each bottle ₃ 200 mM), final ferric chloride concentration of 0.4mM; after shaking and mixing, the bottle was filled with a nickel chloride mother liquor (NiCl) ₂ 200 mM), the final concentration of nickel chloride is 2.0mM, and after shaking uniformly, the serum bottle is placed in a 30 ℃ constant temperature shaking table with the rotating speed of 200rpm for reaction incubation. After incubation for 22h, the sediment containing somatic cells and black particles was collected by centrifugation, washed twice (10000 g, 6min) with ultrapure water, and the resulting material was dried in a vacuum freeze-dryer for 24h.

(4) Heat treatment of the NiFeS nano composite material: and (3) fully grinding the obtained dried sample, placing the sample in a tubular furnace, heating to 300 ℃ at the speed of 5 ℃/min, and annealing for 2h in an argon atmosphere with the flow rate of 60 mL/min. And after the sample to be subjected to heat treatment is naturally cooled to room temperature, placing the obtained catalyst in an oxygen-free closed glass bottle for storage.

All the above operations of collecting bacteria and cleaning samples are completed in the anaerobic workstation.

The biosynthetic NiFeS nanocomposites (denoted as product 1) prepared in step (4) of this example were subjected to material characterization and performance testing:

the product 1 obtained in example 1 was fully ground and a suitable amount of powder was taken for TEM characterization. FIG. 1A is a TEM image of product 1 obtained in example 1, from which it can be seen in FIG. 1A that the black deposit in the synthesis system consists mainly of spherical nanoparticles of uniform size, with an average size of 39.5. + -. 5.6nm. FIG. 1B is an HRTEM image of product 1 obtained in example 1, and calculated lattice spacings in the HRTEM result are 0.231nm and 0.192nm, respectively, which correspond to Ni _0.96 (101) and (102) crystal planes of S.

The product 1 obtained in example 1 is fully ground, and then a proper amount of powder is taken for XRD characterization, and figure 2 is an XRD spectrum of the product 1 obtained in example 1. As compared with a standard card (JADE 6 No.75-0600 _0.96 Characteristic peaks of (100), (101), (102), and (110) crystal planes of S correspond to the biosynthetic monometallic nickel sulfide (Ni) _0.96 S) the XRD characteristic peaks are basically completely matched; characteristic peak and Fe shown at 2 θ =31.4 ° _0.95 S _1.05 The characteristic peak of the (002) crystal face of the material corresponds to the characteristic peak, and the successful doping of the iron element in the material is suggested.

The product 1 obtained in example 1 was ground sufficiently and then an appropriate amount of powder was taken for XPS characterization. FIG. 3 is an XPS spectrum of product 1 obtained in example 1. As can be seen from FIG. 3, XPS survey confirmed the presence of Ni, fe, S, O and C in the material; ni _2p 、Fe _2p And S _2p The map confirms the existence of corresponding valence states of each element. Further, by ICP analysis, it was determined that the precise molar ratio of iron to nickel atoms in the material was Ni: fe =2.67 _0.70 Fe _0.26 S。

The above characterization results confirmed that the Vibrio desulfovibrio was used as the cell factory and Fe was used ³⁺ And Ni ²⁺ The composite material synthesized by the precursor is Ni which consists of Ni, fe and S elements and has a structure doped with Fe _0.96 Iron-nickel sulfide (Ni) with almost uniform S crystal _0.70 Fe _0.26 S)。

The polarization curve test was performed on the product 1 obtained in example 1, and the results are shown in fig. 4. As can be seen from FIG. 4, ni _0.70 Fe _0.26 The overpotential and the Tafel slope of S can be respectively reduced to 247mV and 60.2mV dec ^-1 Is obviously superior to single metal sulfide Ni _0.96 S、Fe _0.95 S _1.05 With commercial electrocatalyst ruthenium dioxide (RuO) ₂ ) This indicates that the resulting product 1 has excellent electrocatalytic properties. When the applied voltage is 1.5V vs RHE, the current density of the material can be 9-11 mA-cm ^-1 The material can continuously operate for more than 4 hours in the range of (1), and the potential of sustainable and stable operation of the material in the actual OER reaction is proved.

Example 2

This example is different from example 1 in that the iron-nickel ratio in the medium was 1 (final concentration of ferric chloride was 1.2mM, and final concentration of nickel chloride was 1.2 mM), and the other examples were the same as example 1.

Example 3

This example is different from example 1 in that the iron-nickel ratio in the medium was 1 (final concentration of ferric chloride was 0.6mM, and final concentration of nickel chloride was 1.8 mM), and the procedure was otherwise the same as example 1.

Example 4

This example was different from example 1 in that the iron-nickel ratio in the medium was 1 (final concentration of ferric chloride was 0.3mM, final concentration of nickel chloride was 2.1 mM), and it was otherwise the same as example 1.

Example 5

This example differs from example 1 in that the NiFeS nanocomposite heat treatment temperature was 200 ℃. The rest is the same as in example 1.

Example 6

This example differs from example 1 in that the NiFeS nanocomposite heat treatment temperature was 400 ℃. The rest is the same as in example 1.

Example 7

This example differs from example 1 in that chemical rich nickel (Ni) is used ²⁺ ) And Sulfates (SO) ₄ ^2- ) The actual electroplating wastewater as nickel source and sulfur source was biosynthesized by the additional addition of iron salt to NiFeS nanocomposite, the other procedure was the same as in example 1.

(1) The basic properties and components of the used electroplating wastewater are as follows: pH 5.2, weak acidity; the contained anions mainly comprise sulfate (32227.2 +/-135.8 mg/L) and nitrate (612.6 +/-3.5 mg/L); the heavy metals mainly comprise nickel (3763.8 +/-29.5 mg/L), iron (54.0 +/-0.3 mg/L) and zinc (26.4 +/-0.2 mg/L).

(2) When the material is synthesized, a certain volume of oxygen-free actual nickel-containing wastewater is added until a certain number of common vibrio desulfurizating bacteria (OD) are inoculated ₆₀₀ = 0.4) serum bottle, ensure initial Ni addition ²⁺ At a concentration of 2.0mM, supplemented with a volume of Fe ³⁺ Mother liquor (FeCl) ₃ 200 mM) to a Fe/Ni molar ratio of 1. After 22h of synthesis, the resulting black sediment was collected by centrifugation, washed and freeze-dried.

(3) And (3) heating the product obtained in the step (2) to 300 ℃ at the speed of 5 ℃/min, and annealing for 2h in an argon atmosphere with the flow rate of 60 mL/min. And after the heat-treated sample is naturally cooled to room temperature, placing the obtained catalyst in an oxygen-free closed glass bottle for storage.

FIG. 5 shows an XRD spectrum and an XPS spectrum of the product (denoted as product 7) obtained in step (3) of example 7 of the present invention. As in example 1, XRD and XPS characterization confirmed that Vibrio desulfurizate was used as a cell factory and Ni in the actual electroplating wastewater ²⁺ And SO ₄ ^2- As nickel source and sulfur source, additionally supplementing Fe ³⁺ Under the condition of being used as an iron source, the synthesized composite material is Ni which consists of Ni, fe and S elements and has a structure doped with Fe _0.96 S crystals are nearly identical iron nickel sulfide.

FIG. 6 shows LSV polarization curve, EIS curve and stability curve of the product 7 obtained in step (3) of example 7 of the present invention. The results are shown in FIG. 6. As can be seen from FIG. 6, the process of NiFeSThe potential and the Tafel slope can be as low as 253mV and 58.6mV dec ^-1 Superior to commercial ruthenium dioxide catalysts, indicating that the resulting product 7 has excellent electrocatalytic properties. When the applied voltage is 1.5V vs RHE, the current density of the material can be 9-11 mA-cm ^-1 The material can continuously operate for more than 4 hours in the range of (1), and the material is proved to have the potential of continuous and stable operation in the actual OER reaction.

The results prove the feasibility of recovering heavy metals from practical electroplating wastewater by using sulfate reducing bacteria and synthesizing high-performance electrocatalysts, and show that the technology has potential good application prospects in the fields of heavy metal wastewater treatment, resource recovery and renewable energy production.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims (10)

1. A preparation method of a bimetallic iron-nickel sulfide nano composite material is characterized by comprising the following steps:

s1, under the anaerobic condition, carrying out shake culture on sulfate reducing bacteria in a culture solution containing water-soluble ferric salt, water-soluble divalent nickel salt and a water-soluble sulfur-containing compound to obtain the NiFeS nano composite material.

2. The method according to claim 1, wherein the sulfate-reducing bacteria is one or more of Vibrio desulfovis, pseudomonas desulforum, phyllobacterium desulforum, and Enterobacter desulforum.

3. The preparation method according to claim 1, wherein the water-soluble ferric salt is one or more of ferric chloride, ferric sulfate, ferric ammonium sulfate and ferric citrate;

the water-soluble divalent nickel salt is one or more of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate and nickel citrate;

the water-soluble sulfur-containing compound is one or more of thiosulfate, sulfate, sulfite and sulfide.

4. The method according to claim 1, wherein step S1 comprises the steps of:

s11, dispersing sulfate reducing bacteria in the culture solution after deoxygenation and sterilization to obtain a bacterial solution;

and S12, adding water-soluble ferric salt, water-soluble nickel salt and water-soluble sulfur-containing compound into the bacterial liquid under an anaerobic condition to obtain a culture system, and performing shaking culture to obtain the NiFeS nano composite material.

5. The method according to claim 4, wherein the OD of the bacterial suspension obtained in the step (1) ₆₀₀ 0.1 to 3;

the concentration of the ferric iron salt in the culture system in the step (2) is 0.1-10 mmol/L, the concentration of the divalent nickel salt is 0.1-10 mmol/L, and the concentration of the water-soluble sulfur-containing compound is 0.1-10 mmol/L; wherein the molar ratio of iron to nickel elements is 1: (0.1-10).

6. The method according to claim 1, wherein the temperature of the shaking culture is 4 to 50 ℃, the rotation speed of the shaker is 50 to 250rpm, and the time is 24 to 72 hours.

7. The method of claim 1, further comprising the steps of:

s2, centrifuging the product obtained after the shaking culture to collect sediments containing somatic cells and black particles, then cleaning, and drying the obtained material;

and S3, carrying out heat treatment on the product obtained in the step S2, raising the temperature to 100-500 ℃ at a heating rate of 1-10 ℃/min in an argon atmosphere, and keeping the temperature for 0.5-5 h.

8. Use of the production method according to any one of claims 1 to 7 for the treatment of wastewater containing Ni ²⁺ 、Fe ³⁺ And a water-soluble sulfur-containing compound.

9. A bimetallic iron-nickel sulfide nanocomposite material characterized by being produced by the production method according to any one of claims 1 to 7.

10. Use of the bimetallic iron nickel sulfide nanocomposite material of claim 9 in electrocatalytic reactions, including one or more of electrocatalytic oxygen evolution, hydrogen evolution and oxygen reduction reactions.

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