Method for synthesizing antimony sulfide photocatalytic nano-material by using antimony-containing wastewater through sulfur reducing bacteria and application of antimony sulfide photocatalytic nano-material

Abstract

The invention relates to the field of synthesis of photocatalytic nano-materials, in particular to a method for synthesizing an antimony sulfide photocatalytic nano-material from antimony-containing wastewater through sulfur reducing bacteria and application of the antimony sulfide photocatalytic nano-material. 2) adding thiosulfate and a carbon source into an anaerobic bottle filled with the antimony-containing wastewater; and (3) centrifuging the activated sulfur reducing bacteria, pouring out supernate, cleaning, pouring into an anaerobic bottle, carrying out anaerobic culture for a period of time, centrifuging, collecting a yellow solid precipitate, and freeze-drying the obtained precipitate, so as to obtain the Sb2S3 photocatalytic nano material. According to the present invention, the antimony-containing wastewater in the industrial mining area is directly treated by using the sulfur reducing bacteria Shewanella sp.ANA-3, and the obtained antimony sulfide precipitate is not subjected to complex treatment to obtain the antimony sulfide photocatalytic nano-material, such that the antimony sulfide photocatalytic nano-material can be used for photocatalytic degradation of azo organic pollutants, and has good photocatalytic effect.

Description

Technical Field

[0001] The invention relates to the field of synthesizing photocatalytic nanomaterials, and in particular to a method and application of synthesizing antimony sulfide photocatalytic nanomaterials by using antimony-containing wastewater with sulfur-reducing bacteria. Background Art

[0002] Antimony sulfide (Sb2S3) nanomaterials have excellent optoelectronic properties, and their band gap (1.78-2.5eV) covers the visible light and near-infrared regions, and are widely used in electrodes, optoelectronics, catalysis, sensors and other fields. At present, most nano antimony sulfide is synthesized by physical and chemical methods, such as template method, hydrothermal method, solvent thermal method, sol-gel method, reflux method, microwave method, sonochemical method, etc. However, physical and chemical methods involve high temperature and high pressure, biohazardous radiation or the use of toxic chemicals. Therefore, the biological synthesis method has great application potential due to its advantages of safety, environmental protection and low cost.

[0003] Invention patent CN110257311A discloses a method of preparing broccoli-shaped antimony sulfide using marine bacteria Halomonas sp.X3, which is used to accelerate the photodegradation of azo dye compounds. The bacteria need to be cultured in a 1-7% salinity medium for 10 days, and the resulting precipitate needs to be resuspended with a cationic surfactant, treated in a hot water bath, and finally freeze-dried to obtain the final nano Sb2S3. The growth conditions of this bacteria are relatively harsh, and the treatment of the precipitate is relatively complicated.

[0004] In view of this, in order to solve a series of problems in the current physical and chemical methods of preparing antimony sulfide photocatalytic nanomaterials, make the microbial synthesis method simpler to operate and more efficient in the actual treatment of antimony-containing wastewater, research on how to use sulfur-reducing bacteria to treat antimony-containing wastewater to synthesize antimony sulfide nanophotocatalytic materials will help develop an efficient and low-cost antimony-containing wastewater treatment technology, and will provide new ideas and methods for the application of nanomaterials in the field of environmental governance. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the purpose of the present invention is to propose a method and application of synthesizing antimony sulfide photocatalytic nanomaterials using antimony-containing wastewater by sulfur-reducing bacteria. In the present invention, sulfur-reducing bacteria Shewanella sp. ANA-3 are directly used to treat antimony-containing wastewater in industrial mining areas, and the obtained antimony sulfide precipitate is not subjected to complicated treatment to obtain antimony sulfide photocatalytic nanomaterials, which can be used for the photocatalytic degradation of azo organic pollutants and have good photocatalytic effect.

[0006] To achieve the above object, the present invention is implemented by the following technical solutions:

[0007] The present invention provides a method for synthesizing antimony sulfide photocatalytic nanomaterials by using sulfur-reducing bacteria and antimony-containing wastewater, comprising the following steps:

[0008] 1) Activating sulfur-reducing bacteria;

[0009] 2) adding thiosulfate and a carbon source into an anaerobic bottle containing antimony-containing wastewater;

[0010] 3) The activated sulfur-reducing bacteria are centrifuged, the supernatant is discarded, and the bacteria are poured into an anaerobic bottle after washing. After anaerobic culture for a period of time, the yellow solid precipitate is collected by centrifugation, and the obtained precipitate is freeze-dried to obtain Sb2S3 photocatalytic nanomaterials.

[0011] As a further optimization scheme of the present invention, in step 1), the sulfur-reducing bacteria include but are not limited to Shewanella sp. ANA-3.

[0012] As a further optimization scheme of the present invention, in step 2), the thiosulfate includes sodium thiosulfate.

[0013] As a further optimization scheme of the present invention, in step 2), the carbon source includes sodium lactate.

[0014] In the above scheme, firstly, the main function of sodium thiosulfate (Na2S2O3) is to serve as a sulfur source. Under the action of sulfur-reducing bacteria, sodium thiosulfate can be reduced to sulfide ions (S 2- These sulfur ions then react with antimony ions (Sb 3+ ) combines to form antimony sulfide (Sb2S3) precipitation. This is one of the key steps in the synthesis of antimony sulfide photocatalytic nanomaterials, because antimony sulfide is the main component of the target product. Secondly, sodium lactate (CH3CHOHCOONa) is mainly used as a carbon source and energy substance. Under anaerobic conditions, sulfur-reducing bacteria require a carbon source for growth and metabolism, and sodium lactate provides such a carbon source. At the same time, the oxidation process of sodium lactate also provides the necessary energy for sulfur-reducing bacteria to support their life activities and reduction reactions. The combined effect of sodium thiosulfate and sodium lactate promotes the synthesis of antimony sulfide photocatalytic nanomaterials.

[0015] As a further optimization scheme of the present invention, in step 1), the sulfur-reducing bacteria are activated using a culture medium. The sulfur-reducing bacteria are activated using LB culture medium, which improves the activity and metabolic capacity of the strains. The activated strains can better adapt to the experimental conditions, thereby improving the synthesis efficiency of antimony sulfide photocatalytic nanomaterials.

[0016] As a further optimization scheme of the present invention, in step 2), sodium thiosulfate and sodium lactate need to be filtered and sterilized before adding. Filtering and sterilizing sodium thiosulfate and sodium lactate prevents contamination by miscellaneous bacteria and ensures the purity of the experiment and the accuracy of the results.

[0017] As a further optimization scheme of the present invention, in step 2), the anaerobic culture conditions are: temperature in the range of 20-40°C, pH in the range of 6.5-8.5, and culture time of 24-96h. This scheme sets the temperature, pH range and culture time in the anaerobic bottle, providing the best conditions for the growth and metabolism of sulfur-reducing bacteria. Sulfur-reducing bacteria can reduce thiosulfate to reduced sulfur in the anaerobic environment, and the reduced sulfur and antimony in the wastewater generate yellow antimony sulfide (Sb2S3) nanoparticles. The appropriate temperature, pH range and culture time are conducive to the formation of stable and high-quality antimony sulfide photocatalytic nanomaterials.

[0018] As a further optimization scheme of the present invention, in step 3), the activated sulfur-reducing bacteria are centrifuged at a speed of 5500-6500 rpm for 5-10 min. The speed and time of centrifugal separation of activated sulfur-reducing bacteria are set to ensure effective separation of the bacteria and removal of the supernatant.

[0019] As a further optimization scheme of the present invention, in step 3), the yellow precipitate in the anaerobic bottle is centrifuged at a speed of 9500-10500 rpm for 10-15 min. The speed and time of centrifuging the yellow precipitate in the anaerobic bottle are set to ensure the effective collection of antimony sulfide photocatalytic nanomaterials.

[0020] As a further optimization scheme of the present invention, the antimony-containing wastewater comes from industrial mining areas. The source of the antimony-containing wastewater (industrial mining areas) is clarified, and harmful antimony-containing wastewater is converted into useful photocatalytic materials, thus realizing the resource utilization of waste.

[0021] The present invention also provides an application of an antimony sulfide photocatalytic nano material in photocatalytic degradation of azo organic pollutants. The antimony sulfide photocatalytic nano material is prepared by the method described.

[0022] Compared with the prior art, the technical solution provided by the present invention has the following advantages and beneficial effects:

[0023] (1) In practical applications, the present invention can directly treat antimony-containing wastewater in industrial mining areas. At the same time, the resulting precipitate does not require complicated treatment. Moreover, since antimony sulfide is a solid catalyst, it is easy to separate from water and can be recycled and reused for photocatalytic degradation of organic pollutants such as azo dyes.

[0024] (2) Experiments have shown that, compared with chemically prepared antimony sulfide and standard antimony sulfide, the photocatalytic degradation rate of methyl orange by the antimony sulfide photocatalyst prepared by the present invention is 84.6%, and the first-order kinetics is 0.01104 min. -1 , with high photocatalytic degradation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1These are photos of anaerobic bottles during the anaerobic co-cultivation of Shewanella sp. ANA-3 and antimony-containing wastewater in Examples 1 to 3 and Comparative Example 1. Figure 1 a, b, c, and d are photos taken after 0h, 24h, 48h, and 96h of co-culture, respectively.

[0026] Figure 2 This is a graph showing the change in dissolved antimony content in antimony-containing wastewater over time during the anaerobic co-cultivation of Shewanella sp. ANA-3 and antimony-containing wastewater in Example 1 and Comparative Example 2.

[0027] Figure 3 This is a high-resolution transmission electron microscopy (HRTEM) image of the solid after centrifugal freeze-drying in Example 1. Figure 3 a, b, and c are HRTEM images at scales of 50nm, 50nm, and 20nm, respectively.

[0028] Figure 4 This is a performance diagram of photocatalytic degradation of methyl orange under visible light for Sb2S3 prepared in Example 1, Comparative Example 3, and commercially purchased Sb2S3. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific embodiments, but it should not be understood as limiting the present invention and is only used as an example.

[0030] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0031] Example 1

[0032] Step 1: First, prepare LB solid culture medium, streak the frozen strain ANA-3 into the LB solid culture medium, place it in a constant temperature incubator at 30 degrees Celsius for 48 hours, and then inoculate LB liquid culture medium in a clean bench to activate Shewanella sp. ANA-3.

[0033] Step 2: Take 50 mL of bacterial solution in a centrifuge tube, centrifuge it at 6000 rpm for 5 minutes, and take 40 mL of antimony-containing water sample to resuspend the bacteria.

[0034] Step 3: In the anaerobic glove box, pour 100 mL of antimony-containing water sample into the anaerobic bottle and 2- The molar ratio of Sb to Sb is 3:4, and filtered sodium thiosulfate and sodium lactate and 10 mL of the resuspended bacterial solution in step 2 are added.

[0035] Step 4: Place the anaerobic bottle in a constant temperature incubator and incubate at 30°C and pH = 7.5 for 96 hours to prepare Sb2S3. Take samples every 24 hours to measure the total amount of antimony. The final results are as follows: Figure 2 .

[0036] Step 5: Centrifuge the water sample in the anaerobic bottle, collect the solid precipitate, and cool and dry the precipitate. Figure 3 It can be seen that the precipitated solid is a spherical nanomaterial with a particle size of approximately 100 nm.

[0037] Example 2

[0038] The difference between this example and Example 1 is that the culture time in step 4 is adjusted to 48 hours, and the rest is the same as Example 1.

[0039] Example 3

[0040] The difference between this example and Example 1 is that the culture time in step 4 is adjusted to 24 hours, and the rest is the same as Example 1.

[0041] Comparative Example 1

[0042] The difference between this example and Example 1 is that the culture time in step 4 is adjusted to 0 h, and the rest is the same as Example 1.

[0043] Comparative Example 2

[0044] The difference between this example and Example 1 is that Shewanella sp. ANA-3 is not added, and the rest is the same as Example 1.

[0045] Figure 1 These are photos of anaerobic bottles during the anaerobic co-cultivation of Shewanella sp. ANA-3 and antimony-containing wastewater in Examples 1 to 3 and Comparative Example 1. Figure 1 a, b, c, and d are photos taken after 0h, 24h, 48h, and 96h of co-culture, respectively. Figure 1 It can be observed that the color changes significantly after 24 hours, turning yellow. As time goes by, the color gradually darkens, and obvious yellow floccules can be seen suspended in the water sample. At 96 hours, there is obvious precipitation at the bottom of the anaerobic bottle. This phenomenon indicates the formation of antimony sulfide.

[0046] Figure 2 The figure is a graph showing the time-dependent change of dissolved antimony content in antimony-containing wastewater during the anaerobic co-culture of Shewanella sp.ANA-3 and antimony-containing wastewater in Example 1 and Comparative Example 2. The circular line is the control group without ANA-3 bacteria (Sb w / oANA-S), and the square line is the experimental group with ANA-3 bacteria (Sb with ANA-3). Figure 2It can be seen that after adding Shewanella sp.ANA-3, the Sb content in the water sample decreased significantly, from 5.6 mg / L to 0.16 mg / L in 144 hours, and the removal rate was 97%.

[0047] Comparative Example 3

[0048] Chemical preparation method of Sb2S3 photocatalyst

[0049] First, 0.5 mM Sb 3+ (Potassium antimony tartrate) (0.6138g potassium antimony tartrate) + 0.75mM Na2S (0.0585g) were added to the anaerobic culture medium, and then sterile hydrochloric acid filtered three times with a 0.22μm pore filter was added to adjust the pH to 7.5. After reacting for 96h, the solid was collected and freeze-dried.

[0050] The photocatalytic degradation performance of methyl orange under visible light of Sb2S3 prepared in Example 1 and Comparative Example 3 and commercially purchased Sb2S3 is tested as follows:

[0051] The photocatalytic degradation performance of the catalyst was measured using a xenon lamp (solar simulated irradiation AM 1.5G) as the light source and methyl orange (MO) as a representative of azo organic pollutants. The freeze-dried samples (10 mg) of Example 1 and Comparative Example 3 and commercially purchased Sb2S3 (10 mg) were dispersed in 25 mL of methyl orange solution with a concentration of 20 mg / L, stirred with a magnetic stirrer, and the dispersion was kept in a dark environment for 2 hours. Then the light source was turned on, and 5 mL of the dispersion was collected every 10 minutes to detect the MO concentration.

[0052] Figure 4 The performance graph of photocatalytic degradation of methyl orange under visible light for Sb2S3 prepared in Example 1 and Comparative Example 3 and commercially purchased Sb2S3. The circular marking line represents the photocatalytic degradation of methyl orange by commercially purchased Sb2S3 (commercially purchased Sb2S3), the square marking line represents the photocatalytic degradation of methyl orange by Sb2S3 generated by the chemical reaction of sodium sulfide and potassium antimony tartrate in Comparative Example 3 (chemically synthesized Sb2S3), and the triangular marking line represents the photocatalytic degradation of methyl orange by antimony sulfide nanomaterials generated by co-cultivation of Shewanella sp. ANA-3 and antimony-containing wastewater in Example 1 (ANA-3 synthesized Sb2S3). Figure 4 It can be seen that the antimony sulfide prepared by Shewanella sp.ANA-3 has a good photocatalytic degradation effect on methyl orange, with a degradation rate of 84.6% within 96 hours and a first-order kinetics of 0.01104min-1. However, commercially purchased and chemically synthesized Sb2S3 do not have the ability to degrade methyl orange under visible light.

[0053] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for synthesizing antimony sulfide photocatalytic nanomaterials using sulfur-reducing bacteria and antimony-containing wastewater, characterized in that: The steps include: 1) Activating sulfur-reducing bacteria; 2) adding thiosulfate and a carbon source into an anaerobic bottle containing antimony-containing wastewater; 3) The activated sulfur-reducing bacteria are centrifuged, the supernatant is discarded, and the bacteria are poured into an anaerobic bottle after washing. After anaerobic culture for a period of time, the yellow solid precipitate is collected by centrifugation, and the obtained precipitate is freeze-dried to obtain Sb2S3 photocatalytic nanomaterials.

2. The method for synthesizing antimony sulfide photocatalytic nanomaterials using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: In step 1), the sulfur-reducing bacteria include Shewanella sp. ANA-3.

3. The method for synthesizing antimony sulfide photocatalytic nanomaterials using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: In step 1), the sulfur-reducing bacteria are activated using a culture medium.

4. The method for synthesizing antimony sulfide photocatalytic nanomaterials using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: In step 2), the thiosulfate includes sodium thiosulfate.

5. The method for synthesizing antimony sulfide photocatalytic nanomaterials by using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: In step 2), the carbon source includes sodium lactate.

6. The method for synthesizing antimony sulfide photocatalytic nanomaterials using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: In step 2), a filtration sterilization operation is required before adding sodium thiosulfate and sodium lactate.

7. The method for synthesizing antimony sulfide photocatalytic nanomaterials using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: In step 3), the anaerobic culture conditions are: temperature in the range of 20-40° C., pH in the range of 6.5-8.5, and culture time of 24-96 hours.

8. The method for synthesizing antimony sulfide photocatalytic nanomaterials by using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: In step 3), the activated sulfur-reducing bacteria are centrifuged at a speed of 5500-6500 rpm for 5-10 min; the yellow precipitate in the anaerobic bottle is centrifuged at a speed of 9500-10500 rpm for 10-15 min.

9. The method for synthesizing antimony sulfide photocatalytic nanomaterials using sulfur-reducing bacteria and antimony-containing wastewater according to claim 1, characterized in that: The antimony-containing wastewater comes from an industrial mining area.

10. Application of antimony sulfide photocatalytic nanomaterials in photocatalytic degradation of azo organic pollutants, characterized in that: The antimony sulfide photocatalytic nanomaterial is prepared by the method according to any one of claims 1-9.

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