Microbial dust suppressant reinforced by utilizing extracellular polymeric substance as well as preparation method and application of microbial dust suppressant

Abstract

The invention provides a microbial dust suppressant reinforced by an extracellular polymeric substance as well as a preparation method and application of the microbial dust suppressant, and belongs to the technical field of dust prevention and dust suppression of coal mines. The preparation method comprises the following steps: adding at least one of a chitosan solution and a bovine serum albumin solution into a culture medium, and adding a bacterial solution; mixing calcium chloride and urea to form a cementing liquid; and mixing the cementing liquid with the cultured bacterial liquid added with at least one of the CTS solution and the BSA solution to obtain the extracellular polymeric substance reinforced microbial dust suppressant. According to the invention, consolidation layers of coal dust can be increased, nucleation sites are increased, calcium carbonate precipitation is promoted, secondary pollution is avoided, the effect is good, and the cost is low. Compared with a common microorganism dust suppressant, the environment-friendly dust suppressant has the characteristics of being environment-friendly and fast in dust suppression effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of dust prevention and suppression in coal mines, and specifically relates to a microbial dust suppressant enhanced by using extracellular polymers (EPS), and a preparation method and application thereof. Background Art

[0002] Coal is the main energy source consumed in my country, and its production scale and consumption level are among the highest in the world. However, a large amount of coal dust will be generated during large-scale coal mining, storage and transportation. Coal dust, as the main pollutant in coal mining, has a great impact on the human body and the environment. First, coal mine workers are in a dusty environment for a long time, and inhaling respirable dust will increase the probability of pneumoconiosis and other diseases; secondly, when the coal dust reaches a certain concentration, it will explode and cause accidents; finally, dust will accelerate the loss of equipment, reduce accuracy, and dust will pollute the environment. Based on this, spraying dust suppressants is the main means of suppressing dust. At present, chemical dust suppressants have problems such as high cost and easy secondary pollution that are difficult to solve. Therefore, the study of green, efficient and pollution-free microbial dust suppressants is the key to solving the dust suppressant problem. Microbial dust suppressants are based on the mineralization of urease-producing microorganisms to produce calcium carbonate for dust suppression. However, it takes a certain amount of time for urease-producing bacteria to metabolize and mineralize, so microbial dust suppressants generally have the problems of low early dust suppression efficiency and few nucleation sites.

[0003] Extracellular polymer substances (EPS) are highly hydrated matrices produced by bacteria. They are high molecular weight organic substances wrapped around the surface of microorganisms. They attach to the surface of biological cells and aggregate into flocs. EPS contains various polymers such as polysaccharides, proteins, lipids and DNA, whose concentrations, ions and functional groups provide physical stability for EPS. The components of EPS form a three-dimensional structure, which degrades nutrients into small molecules for absorption. The structural and functional diversity of EPS depends on specific glycosyltransferases, polymerases and transporters, which are encoded by specific genes in the operon and regulate the biosynthesis of polymers such as curdlan, alginate, colloidal acid and xanthan gum, respectively. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention provides a microbial dust suppressant enhanced by extracellular polymers, and a preparation method and application thereof. The present invention utilizes extracellular polymers to enhance the microbial dust suppressant. EPS can be used as a carrier to increase the nucleation sites in the mineralization process, inducing an increase in the amount of calcium carbonate precipitation; at the same time, the addition of EPS model components can accelerate the dust suppression process and achieve early dust suppression; thus providing a green, efficient, pollution-free, and mineralization time-reducing EPS enhanced microbial dust suppression method for coal dust prevention and control. The technical scheme of the present invention is as follows: A method for preparing a microbial dust suppressant enhanced by extracellular polymers, the specific steps are as follows: (1) Dissolve chitosan in a 1% by mass acetic acid solution, and adjust the pH to 6.5-7.0 with a sodium hydroxide solution to obtain a chitosan solution (CTS solution); dissolve bovine serum albumin in distilled water to prepare a bovine serum albumin solution (BSA solution); (2) After mixing peptone, meat extract and water, add sodium hydroxide solution to adjust the pH, add filtered and sterilized urea solution after sterilization to obtain a culture medium, and then add bacterial solution; add at least one of the CTS solution and BSA solution prepared in step (1) to the culture medium containing the bacterial solution to obtain a mixed solution, and culture it in a constant temperature shaking incubator; (3) Mixing calcium chloride solution and urea solution to form a cementing solution; (4) The binder liquid prepared in step (3) is mixed with the mixed liquid obtained in step (2) to obtain an extracellular polymer-enhanced microbial dust suppressant.

[0005] Preferably, the concentrations of the chitosan and bovine serum albumin solutions in step (1) are both 0.5-2 g / L; and the molar concentration of the sodium hydroxide solution for adjusting the pH is 0.1 mol / L.

[0006] Preferably, the concentrations of the components in the culture medium in step (2) are: urea 20 g / L, peptone 5 g / L, meat extract 3 g / L. Preferably, in step (2), the concentration of the sodium hydroxide solution is 4 g / L, and the pH is adjusted to 7.

[0007] Preferably, the bacteria in the bacterial solution in step (2) are Sporosarcina pasteurii, and the bacterial concentration in the bacterial solution is about 1×10 7 ~1×10 10 CFU / mL.

[0008] Preferably, in step (2), the volume ratio of the composite ratio CTS:BSA is (1-2):(1-2), and the concentrations of CTS and BSA are both 2 g / L; more preferably, the volume ratio of CTS:BSA is 1:2.

[0009] Preferably, in step (2), the volume ratio of the single solution or the composite solution of the CTS solution and the BSA solution, the bacterial solution and the culture medium is 3:1:65.

[0010] Preferably, the culture conditions in step (2) are a shaking speed of 150 rpm, a culture temperature of 25° C., and a culture time of 24 h.

[0011] Preferably, in step (3), the concentrations of the calcium chloride solution and the urea solution are both 0.5 mol / L, and the solvent is water; and the volume ratio of the calcium chloride solution to the urea solution in the binder is 1:1.

[0012] Preferably, in step (4), the volume ratio of the binder to the mixed liquid is 1:1.

[0013] The present invention also includes the use of the above-mentioned EPS-reinforced microbial dust suppressant, including: ① Dust suppression on both sides of the road ② Dust suppression in spoil dump ③ Coal dust suppression in open-pit coal mines The EPS-reinforced microbial dust suppressant of the present invention mainly utilizes the added chitosan and bovine serum protein components to provide nucleation sites in the mineralization process and promote the generation of calcium carbonate.

[0014] Compared with the prior art, the present invention has the following advantages: (1) The EPS-reinforced microbial dust suppressant of the present invention is added with chitosan and bovine serum protein model components, which increases the penetration of the bacterial solution during use, can increase the consolidation layer of coal dust, increase nucleation sites and promote calcium carbonate precipitation.

[0015] (2) The dust suppressant of the present invention is produced by urease-producing bacteria, which decomposes urea to produce carbonate ions. These carbonate ions combine with calcium ions in the cementing fluid to form calcium carbonate precipitation. This process is easy to control and is green and pollution-free.

[0016] (3) The mineralization of bacteria forms a consolidation layer on the surface of the coal dust to suppress dust, which will not cause secondary pollution. It has good effects and low costs.

[0017] (4) Compared with common microbial dust suppressants, the EPS-enhanced microbial dust suppressant of the present invention is green and environmentally friendly, and has a fast dust suppression effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The calcium carbonate yield of the single-component EPS-enhanced microbial dust suppressant at different concentrations and mineralization times; Figure 2 The wind erosion rate of coal dust at different times after being treated with microbial dust suppressants enhanced by single-component EPS at different concentrations; Figure 3 The wind erosion rate of coal powder treated with microbial dust suppressants reinforced with composite EPS in different proportions. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with specific embodiments, and the advantages of the present invention will become clearer as the description proceeds.

[0020] Embodiment 1: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Chitosan was dissolved in a 1% glacial acetic acid solution at a concentration of 0.5 g / L and the pH value was adjusted to 6.8 with a sodium hydroxide solution to obtain a chitosan solution.

[0021] (2) Dissolve 5 g of peptone and 3 g of meat extract in 900 mL of water, adjust the pH to 7 with sodium hydroxide solution, and sterilize in an autoclave at 121°C for 20 min. Dissolve 20 g of urea in 100 mL of water, filter and sterilize with a filter, then add to the sterilized and cooled peptone and meat extract solution to obtain a culture medium, add the bacterial solution, and add a chitosan solution with a concentration of 0.5 g / L. The volume ratio of chitosan solution, bacterial solution, and culture medium is 3:1:65 to obtain a mixed solution. Incubate in a constant temperature shaking incubator at 150 rpm and 25°C for 24 h.

[0022] (3) Mix 0.5 mol / L calcium chloride solution and 0.5 mol / L urea solution in a ratio of 1:1 to form a binder.

[0023] (4) The binder obtained in step (3) is mixed with the mixed solution obtained in step (2) in a ratio of 1:1 to obtain an extracellular polymer-enhanced microbial dust suppressant.

[0024] Embodiment 2: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Add chitosan solution with a concentration of 1.0 g / L, and the remaining steps are the same as those in Example 1.

[0025] Embodiment 3: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Add chitosan solution with a concentration of 1.5 g / L, and the remaining steps are the same as those in Example 1.

[0026] Embodiment 4: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Add chitosan solution with a concentration of 2.0 g / L, and the remaining steps are the same as those in Example 1.

[0027] Embodiment 5: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Prepare a bovine serum albumin solution by dissolving bovine serum albumin in distilled water at a concentration of 0.5 g / L.

[0028] (2) Dissolve 5 g of peptone and 3 g of meat extract in 900 mL of water, adjust the pH to 7 with sodium hydroxide solution, and sterilize in an autoclave at 121°C for 20 min. Dissolve 20 g of urea in 100 mL of water, filter and sterilize with a filter, then add to the sterilized and cooled peptone and meat extract solution to obtain a culture medium, add the bacterial solution, add a bovine serum albumin solution with a concentration of 0.5 g / L, and the volume ratio of chitosan solution, bacterial solution and culture medium is 3:1:65 to obtain a mixed solution. Incubate in a constant temperature shaking incubator at 150 rpm and 25°C for 24 h.

[0029] (3) Mix 0.5 mol / L calcium chloride solution and 0.5 mol / L urea solution in a ratio of 1:1 to form a binder.

[0030] (4) The binder obtained in step (3) is mixed with the mixed solution obtained in step (2) in a ratio of 1:1 to obtain a microbial dust suppressant enhanced with extracellular polymers.

[0031] Embodiment 6: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Add a bovine serum albumin solution with a concentration of 1.0 g / L, and the remaining steps are the same as those in Example 5.

[0032] Embodiment 7: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Add a bovine serum albumin solution with a concentration of 1.5 g / L, and the remaining steps are the same as those in Example 5.

[0033] Embodiment 8: A method for preparing a microbial dust suppressant enhanced by using extracellular polymers (1) Add a bovine serum albumin solution with a concentration of 2.0 g / L, and the remaining steps are the same as those in Example 5.

[0034] Comparative Example 1: A method for enhancing bacterial dust suppression using extracellular polymers Dissolve 5 g of peptone and 3 g of meat extract in 900 mL of water, adjust pH to 7 with sodium hydroxide solution, and sterilize in an autoclave at 121°C for 20 min. Dissolve 20 g of urea in 100 mL of water, filter and sterilize with a filter, then add to the sterilized and cooled peptone and meat extract solution to obtain a culture medium, add bacterial solution, and the volume ratio of bacterial solution to culture medium is 1:65. In a constant temperature shaking incubator, 150 rpm, 25°C, culture for 24 h respectively. Add the binder solution and culture for 24 h and 48 h respectively.

[0035] Test Example 1: Calcium carbonate yield of single-component EPS-enhanced microbial dust suppressant at different concentrations and mineralization times The mixed solution obtained in step (2) of Example 1 to Example 8 and the cementing solution obtained in step (3) were mixed in a conical flask at a ratio of 1:1 and cultured for 24 hours and 48 hours to produce a mineralized product.

[0036] Calcium carbonate production test: The conical flask and the obtained mineralized product were dried, and the conical flask and the mineralized product precipitate were weighed, recorded as W1; washed with hydrochloric acid to remove the calcium carbonate precipitate, and weighed again after drying, recorded as W2; the weight of calcium carbonate is W3 (W2-W1), as shown in Table 1 and Figure 1 shown.

[0037] Table 1 Calcium carbonate production of single-component EPS-enhanced microbial dust suppressants at different concentrations and mineralization times

[0038] From Table 1 and Figure 1 It can be seen that the calcium carbonate content gradually increases after adding different concentrations of CTS or BSA to prepare microbial dust suppressants. When the concentration of EPS model components is 2.0 g / L, the content of calcium carbonate produced is the highest. This is because the added model components can increase the urease activity of microorganisms and provide more nucleation sites to precipitate calcium carbonate, thereby increasing the yield of calcium carbonate. In summary, EPS-enhanced microbial dust suppressants can promote the yield of calcium carbonate.

[0039] Test Example 2: Wind erosion rate of coal dust at different times after treatment with microbial dust suppressants enhanced by single-component EPS at different concentrations The EPS-enhanced microbial dust suppressants obtained in Examples 1 to 8 were sprayed onto the surface of the coal powder respectively.

[0040] Dust suppression effect test: Weigh 30 g of coal powder in a culture dish, place the prepared solutions in a spray bottle, and spray the EPS cultured mixed solution and the binding liquid (EPS enhanced microbial dust suppressant) in turn.

[0041] The pulverized coal sprayed with the EPS-enhanced microbial dust suppressant was placed at room temperature to air dry naturally. After 3 days, the pulverized coal was sprayed with the EPS-enhanced microbial dust suppressant again in the above manner. The above operation was repeated 3 times, and the treated pulverized coal was placed at room temperature to air dry naturally for 3 days, 6 days, and 9 days. The treated coal powder was subjected to wind erosion resistance test, where the wind speed was 10 m / s. The results are shown in Table 2 and Figure 2 shown.

[0042] Table 2 Wind erosion rate of coal dust at different times after treatment with microbial dust suppressants enhanced by single-component EPS at different concentrations

[0043] From Table 2 and Figure 2 It can be seen that the loss of the microbial dust suppressant enhanced by EPS after adding CTS and BSA is the smallest when the curing time is 9 days. It can be seen from Table 2 that the loss effect of coal powder with a long treatment time is much better than that of coal powder with a short treatment time. This is because the microbial dust suppressant with a long curing time can produce more mineralized products, which can achieve cementation of coal powder and achieve better dust suppression effect.

[0044] Example 9: A method for enhancing bacterial dust suppression using extracellular polymers (1) Preparation of mixed EPS model components: CTS was dissolved in 1% glacial acetic acid solution (the pH was adjusted to 6.8 with sodium hydroxide) to prepare a CTS solution with a concentration of 2 g / L, and BSA was dissolved in distilled water to prepare a BSA solution with a concentration of 2 g / L. The two solutions were mixed in volume ratios of 1:1, 1:2, and 2:1, respectively, to obtain mixed EPS model component solutions.

[0045] (2) Dissolve 5 g of peptone and 3 g of meat extract in 900 mL of water, adjust the pH to 7 with sodium hydroxide solution, and sterilize in an autoclave at 121°C for 20 min. Dissolve 20 g of urea in 100 mL of water, filter and sterilize with a filter, and then add to the sterilized and cooled peptone and meat extract solution to obtain a culture medium. Add bacterial solution, and add mixed EPS model components of different ratios to the culture medium. The volume ratio of mixed EPS model components, bacterial solution and culture medium is 3:1:65 to obtain a mixed solution. In a constant temperature shaking incubator, culture at 150 rpm and 25°C for 24 h.

[0046] (3) Mix 0.5 mol / L calcium chloride solution and 0.5 mol / L urea solution in a ratio of 1:1 to form a binder.

[0047] (4) The binder obtained in step (3) is mixed with the mixed solution obtained in step (2) in a ratio of 1:1 to obtain a microbial dust suppressant enhanced with extracellular polymers.

[0048] Test Example 3: Wind erosion rate of coal powder treated with microbial dust suppressants reinforced with EPS in different proportions 30 g of coal powder was weighed in a culture dish, and the mixed liquid and the binder liquid obtained from Example 9 and Comparative Example 1 were placed in a spray pot, and the bacterial liquid and the binder liquid (EPS-enhanced microbial dust suppressant) were sprayed in sequence. Finally, the coal powder sprayed with the EPS-enhanced microbial dust suppressant was placed at room temperature to dry naturally, and after 3 days, the EPS-enhanced microbial dust suppressant was sprayed again in the above manner. The above operation was repeated 3 times, and the treated coal was subjected to an anti-wind erosion test on the treated coal powder, where the wind speed was 10 m / s. The results are shown in Table 3 and Figure 3 shown.

[0049] Table 3 Wind erosion rate of coal powder under treatment of microbial dust suppressants reinforced with composite EPS at different ratios

[0050] From Table 3 and Figure 3 It can be seen that after adding different ratios of CTS and BSA mixed with EPS model components to prepare microbial dust suppressants, the coal dust loss rate is greatly reduced. When CTS: BSA is 1:2, the coal dust loss rate is the lowest. This is because the added model components can provide more nucleation sites to precipitate calcium carbonate, increase the yield of calcium carbonate, and the generated calcium carbonate can fill the pores between the coal dust to reduce the loss. When the ratio is 1:2, CTS can improve the adhesion ability of BSA, thereby improving the early dust suppression effect of the microbial dust suppressant. In summary, EPS can enhance the dust suppression effect of bacteria.

Claims

1. A method for preparing a microbial dust suppressant enhanced by extracellular polymers, characterized in that: The specific steps are as follows: (1) Dissolve chitosan in a 1% by mass acetic acid solution, and adjust the pH to 6.5-7.0 with a sodium hydroxide solution to obtain a chitosan solution (CTS solution); dissolve bovine serum albumin in distilled water to prepare a bovine serum albumin solution (BSA solution); (2) After mixing peptone, meat extract and water, add sodium hydroxide solution to adjust the pH, add filtered and sterilized urea solution after sterilization to obtain a culture medium, and then add bacterial solution; add at least one of the CTS solution and BSA solution prepared in step (1) to the culture medium containing the bacterial solution to obtain a mixed solution, and culture it in a constant temperature shaking incubator; (3) Mixing calcium chloride solution and urea solution to form a cementing solution; (4) The binder liquid prepared in step (3) is mixed with the mixed liquid obtained in step (2) to obtain an extracellular polymer-enhanced microbial dust suppressant.

2. The preparation method according to claim 1, characterized in that The concentrations of the chitosan and bovine serum albumin solutions in step (1) are both 0.5-2 g / L; the molar concentration of the sodium hydroxide solution for adjusting the pH is 0.1 mol / L.

3. The preparation method according to claim 1, characterized in that The concentrations of the components in the culture medium in step (2) are: urea 20 g / L, peptone 5 g / L, meat extract 3 g / L; the concentration of the sodium hydroxide solution is 4 g / L, and the pH is adjusted to 7.

4. The preparation method according to claim 1, characterized in that The bacteria in the bacterial solution in step (2) are Sporosarcina pasteurii, and the bacterial concentration in the bacterial solution is about 1×10 7 ~1×10 10 CFU / mL.

5. The preparation method according to claim 1, characterized in that The volume ratio of the composite ratio CTS:BSA in step (2) is (1-2):(1-2), and the concentrations of CTS and BSA are both 2 g / L; preferably, the volume ratio of CTS:BSA is 1:

2.

6. The preparation method according to claim 1, characterized in that In step (2), the volume ratio of the single solution or the composite solution of the CTS solution and the BSA solution, the bacterial solution and the culture medium is 3:1:65; the culture conditions are an oscillation speed of 150 rpm, a culture temperature of 25°C and a culture time of 24 h.

7. The preparation method according to claim 1, characterized in that In step (3), the concentrations of the calcium chloride solution and the urea solution are both 0.5 mol / L, and the solvent is water; the volume ratio of the calcium chloride solution and the urea solution in the binder is 1:

1.

8. The preparation method according to claim 1, characterized in that: In step (4), the volume ratio of the binder to the mixed liquid is 1:

1.

9. An extracellular polymer-enhanced microbial dust suppressant obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the extracellular polymer-enhanced microbial dust suppressant according to claim 9 in suppressing dust on both sides of roads, dust in spoil dumps and coal dust in open-pit coal mines.

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