Preparation method and application of magnetic charcoal-loaded bacterium composite functional material

Abstract

The invention discloses a preparation method and application of a magnetic biochar-loaded bacterium composite functional material, magnetic biochar (MBC) is used as a carrier to load and fix Achromobacter denitrificans BP1 (Achromobacter denitrificans BP1, the NCBI login number is CP154792), and a magnetic biochar-loaded functional bacterium (MBC-coated BP1) is obtained. The invention relates to a water and soil purifying agent which is used for removing pollutants in water and / or soil, the pollutants comprise polycyclic aromatic hydrocarbons (PAHs) and / or heavy metals (HM) and the like, benzo [a] pyrene (BaP) and phenanthrene (Phe) in the soil can be efficiently degraded, Cr (VI) is removed, nitrate (NO3 <->) is metabolized, the soil nutrient level (organic matters, nitrogen, phosphorus and the like) can be increased, the diversity and structural functions of soil microbial communities are improved, and the water and soil purifying agent can be used for purifying water and / or soil. And a green and efficient repairing material and a technical support are provided for a compound pollution complex site.

Description

Technical Field

[0001] The present invention relates to a polycyclic aromatic hydrocarbons (PAHs) pollution and heavy metal (HM) pollution treatment technology, and in particular to a preparation method and application of a magnetic biochar-loaded bacteria composite functional material. Background Art

[0002] Polycyclic aromatic hydrocarbons (PAHs) pollution and heavy metal (HM) pollution are common in industrial sites and surrounding soil. The presence of PAHs and HMs, on the one hand, will affect the activity of microorganisms in the soil and the growth of surface vegetation, thereby affecting the surrounding ecological environment; on the other hand, soil particles will enter the human body through different pathways. If there are farmlands outside the factory, these pollutants will also be absorbed by plants and enter the human body through the food chain, posing certain health risks.

[0003] At present, more than 30 PAHs have been proven to be carcinogenic to varying degrees, including benzo[a]pyrene, phenanthrene, etc. PAHs can persist in the environment and can achieve long-distance migration. They are highly biotoxic and bioaccumulative. Some degradation intermediates of PAHs also have certain toxic effects. HM refers to a specific gravity (density) greater than 4.5g / cm 3 HM in contaminated soil can enter the human body through various ways (such as food chain, inhalation, oral administration, etc.), and the proteins and enzymes in the human body can react strongly, causing the proteins and enzymes to lose their activity. The accumulation of HM in human organs will lead to chronic poisoning of the human body. The degradation of PAHs in soil and the removal of HM have always been a hot topic of research.

[0004] In the prior art, chemical stabilization and chemical oxidation methods are usually used to repair PAHs-HM composite contaminated soil. Although this method has a significant remediation effect, it may introduce new chemical substances, damage the soil microecological environment, seriously reduce soil fertility, and the remediation cost is high. In recent years, biochar has attracted widespread attention due to its low cost and environmental protection. However, the adsorption and remediation efficiency of raw biochar for soil PAHs and HM is low. Modifying biochar to prepare magnetic biochar can increase the specific surface area, pore structure and functional group richness, thereby improving the remediation efficiency. Microbial remediation is inexpensive and green, but it has disadvantages such as low remediation efficiency and long cycle.

[0005] Using magnetic biochar as a carrier to load microorganisms can provide nutrients for microorganisms, comprehensively improve the remediation efficiency, and at the same time regulate the soil microbial community to improve its structure and function, providing technical support for its application and promotion in on-site remediation practice.

[0006] Technical solution of prior art 1:

[0007] Biochar (BC), as a carbon-based material rich in pore structure, has become a promising adsorbent for remediation of environmental pollution. BC has been widely studied as a material for carbon sequestration and remediation of PAHs and HMs due to its adsorption capacity.

[0008] Disadvantages of prior art 1:

[0009] The limited adsorption capacity of original BC for PAHs and HM may lead to its low remediation efficiency. As the remediation time goes by, the aging process of BC in the soil may cause changes in its own structure, thereby causing the re-release of pollutants. BC itself may also cause toxicity to the soil. In addition, centrifugation and filtration are usually required to separate BC powder from the environmental medium, which limits the amount of BC that can be applied and causes secondary pollution.

[0010] Technical solution of the second prior art:

[0011] Microbial remediation is more targeted at removing PAHs because it can metabolize organic pollutants as carbon sources, thereby reducing the content of organic matter in the soil. Microorganisms in the soil reduce the toxicity of HM in the soil by producing oxidation-reduction, adsorption, precipitation and other effects on HM and by mineralizing and consolidating HM ions.

[0012] Disadvantages of the second prior art:

[0013] Hydrophobic PAHs and HMs are not easily utilized by microorganisms, and soil PAHs and HM pollution may harm functional microorganisms. After being added to the soil, functional microorganisms will compete with indigenous microorganisms, resulting in a decrease in the efficiency of microbial remediation of contaminated soil.

[0014] Microorganisms repair HM by absorbing or transforming HM, but they cannot completely remove HM from the soil. When soil environmental conditions change, these HM may be released back into the soil. In addition, considering the complexity of PAHs-HM compound pollution, simple microbial remediation is inefficient and time-consuming, and needs to be combined with other remediation technologies.

[0015] In view of this, the present invention is proposed. Summary of the invention

[0016] The purpose of the present invention is to provide a method for preparing a magnetic biochar-loaded bacteria composite functional material and its application, so as to solve the above-mentioned technical problems existing in the prior art.

[0017] The objective of the present invention is achieved through the following technical solutions:

[0018] The method for preparing the magnetic biochar-loaded bacteria composite functional material of the present invention uses magnetic biochar (MBC) as a carrier to load and fix denitrifying Achromobacter BP1 to obtain the magnetic biochar-loaded bacteria composite functional material;

[0019] The Latin name of the denitrifying Achromobacter BP1 is: Achromobacter denitrificans; and the NCBI accession number is: CP154792.

[0020] Application of the prepared magnetic biochar-loaded bacteria composite functional material:

[0021] Used for removing pollutants in water and / or soil, including polycyclic aromatic hydrocarbons (PAHs) and / or heavy metals (HM);

[0022] Degrade benzo[a]pyrene (BaP) and phenanthrene (Phe) in the soil, remove Cr(VI) and metabolize nitrate (NO3-);

[0023] Increase soil nutrient levels, including organic matter, nitrogen and phosphorus, and improve soil microbial community diversity and structural function.

[0024] Compared with the prior art, the preparation method and application of the magnetic biochar-loaded bacteria composite functional material provided by the present invention can efficiently degrade benzo[a]pyrene (BaP) and phenanthrene (Phe) in the soil, remove Cr(VI) and metabolize nitrate (NO3-), and can also increase the soil nutrient level (organic matter, nitrogen, phosphorus, etc.), improve the diversity and structural function of soil microbial communities, and provide green and efficient remediation materials and technical support for complex and complex contaminated sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic flow chart of a method for preparing a magnetic biochar-loaded bacteria composite functional material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] First, the terms that may be used in this article are explained as follows:

[0028] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0029] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0030] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0031] Unless otherwise specified or limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this article can be understood according to specific circumstances.

[0032] The orientation or position relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the drawings and are only for the convenience and simplification of description, and do not explicitly or implicitly indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation of this document.

[0033] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0034] The method for preparing the magnetic biochar-loaded bacteria composite functional material of the present invention uses magnetic biochar (MBC) as a carrier to load and fix denitrifying Achromobacter BP1 to obtain the magnetic biochar-loaded bacteria composite functional material;

[0035] The Latin name of the denitrifying Achromobacter BP1 is: Achromobacter denitrificans; and the NCBI accession number is: CP154792.

[0036] The preparation method of the magnetic biochar (MBC) is as follows:

[0037] Weigh 70g of crushed rice husk and 1L of mixed salt solution of n(Fe3+):n(Fe2+)=2:1 and fully dissolve and mix at 65℃, add NaOH to increase the pH value to 11.0~12.0, filter the precipitate, rinse with ethanol and dry, load it into a quartz boat and place it in a tube furnace, pass N2 for 30min to make the furnace in an oxygen-deficient atmosphere, anaerobically pyrolyze at 450℃ for 2h, pass through a 200-mesh nylon sieve and store for later use, marked as MBC;

[0038] The preparation method of the magnetic biochar loaded functional bacteria (MBC@BP1) is as follows:

[0039] (1) culturing the functional bacteria to the late logarithmic growth stage, preparing a bacterial suspension, and refrigerating it for later use;

[0040] (2) Weigh 5 g of magnetic biochar and add it to 2 L of denitrifying Achromobacter BP1 suspension. Denitrifying Achromobacter BP1 was adsorbed and loaded in a conical flask at a rotation speed of 150 rpm and a constant temperature of 25 °C. After static sedimentation, the supernatant was poured out and dried in an oven at 30 °C to obtain the magnetic biochar loaded functional bacteria (MBC@BP1).

[0041] Application of the prepared magnetic biochar-loaded bacteria composite functional material:

[0042] Used for removing pollutants in water and / or soil, including polycyclic aromatic hydrocarbons (PAHs) and / or heavy metals (HM);

[0043] Degrade benzo[a]pyrene (BaP) and phenanthrene (Phe) in the soil, remove Cr(VI) and metabolize nitrate (NO3-);

[0044] Increase soil nutrient levels, including organic matter, nitrogen and phosphorus, and improve soil microbial community diversity and structural function.

[0045] In summary, it can be seen that the preparation method and application of the magnetic biochar-loaded bacteria composite functional material of the embodiment of the present invention can efficiently degrade benzo[a]pyrene (BaP) and phenanthrene (Phe) in the soil, remove Cr(VI) and metabolize nitrate (NO3-), and can also increase the soil nutrient level (organic matter, nitrogen, phosphorus, etc.), improve the diversity and structural function of the soil microbial community, and provide green and efficient remediation materials and technical support for complex and complex polluted sites.

[0046] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0047] Example 1

[0048] like Figure 1 As shown:

[0049] The present invention aims at the current situation that PAHs and HM pollution is widespread and compound pollution is complicated in industrial sites. The toxic effects of PAHs and HM in soil may produce synergistic effects under the interaction of various environmental factors in the microenvironment and organisms, making them difficult to control. The use of a single remediation technology to control compound pollution is usually targeted at a certain type of pollutant and requires the use of multiple remediation technologies for control.

[0050] The combination of BC and microbial remediation has attracted widespread attention in recent years due to its low cost and environmental protection. However, the screening of functional microorganisms and the remediation efficiency are also very critical.

[0051] In view of the problems that the original BC has poor adsorption capacity and is easy to age, resulting in unstable remediation, the present invention modifies the original BC by magnetizing (Fe3O4) to prepare magnetic biochar (MBC). MBC has a stronger specific surface area, a more developed pore structure, richer functional groups, and superior stability, and has a stronger pollutant adsorption capacity than native BC. It should be noted that MBC can be isolated from the medium using magnetic materials, thereby simplifying the separation stage, using less energy, and improving the reusability of MBC. MBC is an excellent soil remediation agent for soil remediation because it can not only enhance the physical and chemical properties of the soil, but also efficiently remove or fix PAHs and HM, and at the same time enhance carbon sequestration in the soil.

[0052] The present invention combines the problems of low efficiency and long time of microbial remediation technology, and uses MBC as a carrier to load the microorganism BP1 (BP1 is a strain screened and identified by the inventor) that can efficiently degrade PAHs, remove hexavalent chromium (Cr(VI)), and metabolize nitrates to prepare a magnetic biochar-loaded functional bacteria multifunctional material, which can give full play to the advantages of biochar adsorption and microbial remediation, and can regulate the function of the microbial community while having high efficiency in remediating soil PAHs-HM complex pollution, and promote the evolution of the microbial community in a direction that is conducive to remediation. The magnetic biochar-loaded functional bacteria multifunctional material is low-cost, green and environmentally friendly, has efficient and stable remediation, and is easy to transport. It can provide a new type of material for complex polluted sites and can be applied to a variety of pollution scenarios.

[0053] The present invention aims at the complex PAHs-HM compound pollution in soil and the green and efficient remediation efficiency of the microbial remediation process, and focuses on the efficiency enhancement and application limitations of microbial remediation technology.

[0054] The present invention prepares a novel magnetic biochar-loaded bacteria multifunctional material, which can efficiently degrade benzo[a]pyrene (BaP) and phenanthrene (Phe) in soil, remove Cr(VI) and metabolize nitrate (NO3-), and can also increase soil nutrient levels (organic matter, nitrogen, phosphorus, etc.), improve soil microbial community diversity and structural functions, and provide green and efficient remediation materials and technical support for complex sites with complex pollution. The functional bacteria is a strain of denitrifying colorless bacterium BP1 (Achromobacter denitrificans, NCBI accession number: CP154792) identified by the inventor from a coal chemical site in Taiyuan, China in the early stage. It exhibits excellent Cr(VI) reduction ability while efficiently degrading BaP, Phe, etc., and has NO3- metabolism ability.

[0055] The preparation method of magnetic biochar (MBC) is the co-sedimentation method. The main mechanism of the reaction is Fe2++2Fe3++8OH-→Fe3O4+4H2O. The specific preparation method is as follows: weigh an appropriate amount of crushed rice husk and a mixed salt solution of n(Fe3+):n(Fe2+)=2:1, and fully dissolve and mix them at 65°C. Add NaOH to increase the pH value to 11.0-12.0. After filtering the precipitate, rinse it with ethanol and dry it. Load it into a quartz boat and place it in a tubular furnace. Pass N2 for 30 minutes to make the furnace in an oxygen-deficient atmosphere. Anaerobic pyrolysis is carried out at 450°C for 2 hours. After passing through a 200-mesh nylon sieve, it is stored for later use and marked as MBC.

[0056] The preparation method of magnetic biochar loaded functional bacteria (MBC@BP1) is as follows: (1) culturing the functional bacteria to the late logarithmic growth stage, preparing a bacterial suspension, and refrigerating it in a refrigerator for later use; (2) weighing a certain amount of magnetic biochar and adding it to the BP1 bacterial suspension, adsorbing and loading the bacterial community BP1 in a conical flask at a rotation speed of 150 rpm and a constant temperature of 25°C, pouring out the supernatant after static sedimentation, and drying it in an oven at 30°C to obtain the magnetic biochar loaded functional bacteria (MBC@BP1).

[0057] Based on the current status of soil PAHs-HM pollution, the present invention prepares and optimizes magnetic biochar-loaded microbial multifunctional materials with the overall goal of improving microbial remediation of contaminated soil and enhancing its remediation effect, and investigates its remediation efficiency for soil PAHs, Cr(VI), and NO3-. This invention can provide a new type of green, efficient, and ecological remediation functional material for PAHs-HM contaminated soil, and provide important technical reference and theoretical basis for the technical development and application of green and sustainable remediation of PAHs-HM contaminated soil.

[0058] The present invention imparts magnetism to biochar by co-precipitation followed by pyrolysis to prepare magnetic biochar, and can also prepare magnetic biochar by one-step pyrolysis, microwave pyrolysis, etc. Similarly, the present invention prepares magnetic biochar-loaded bacteria composite functional materials based on the adsorption method, and can also prepare them by the embedding method, but the prepared materials are different.

[0059] However, the strain BP1 in the magnetic biochar-loaded bacteria composite functional material was screened and identified by the inventors themselves.

[0060] The key technical points of the present invention are:

[0061] 1. Using magnetic biochar as a carrier to load and fix BP1 can greatly improve the removal efficiency of BP1 for pollutants such as PAHs and HM;

[0062] 2. Biochar carriers can improve the dispersion and colonization rate of BP1 in the soil, prompting the soil microbial community to evolve faster in the direction of improving functionality;

[0063] 3. Biochar magnetization can be easily recycled, realizing the reuse of magnetic biochar-loaded bacteria multifunctional materials, while avoiding the risk of secondary release of pollutants caused by the aging of biochar itself;

[0064] 4. Applying biochar to the soil can significantly increase the soil organic matter content and fertility level, while also playing a role in carbon fixation, helping to achieve the "dual carbon" goals with green and sustainable restoration technology.

[0065] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing a magnetic biochar-loaded bacteria composite functional material, characterized in that: Magnetic biochar (MBC) was used as a carrier to load and immobilize Achromobacter denitrificans BP1 to obtain a composite functional material of magnetic biochar loaded bacteria. The Latin name of the denitrifying Achromobacter BP1 is: Achromobacter denitrificans; and the NCBI accession number is: CP154792.

2. The method for preparing the magnetic biochar-loaded bacteria composite functional material according to claim 1, characterized in that: The preparation method of the magnetic biochar (MBC) is as follows: Weigh 70 g of crushed rice husk and 1 L of mixed salt solution of n(Fe3+):n(Fe2+)=2:1 and fully dissolve and mix them at 65°C. Add NaOH to increase the pH value to 11.0-12.

0. After filtering the precipitate, rinse it with ethanol and dry it. Load it into a quartz boat and place it in a tubular furnace. Pass N2 for 30 minutes to create an oxygen-deficient atmosphere in the furnace. Anaerobic pyrolysis is carried out at 450°C for 2 hours. After passing through a 200-mesh nylon sieve, it is stored for later use and marked as MBC.

3. The method for preparing the magnetic biochar-loaded bacteria composite functional material according to claim 2, characterized in that: The preparation method of the magnetic biochar loaded functional bacteria (MBC@BP1) is as follows: (1) culturing the functional bacteria to the late logarithmic growth stage, preparing a bacterial suspension, and refrigerating it for later use; (2) Weigh 5 g of magnetic biochar and add it to 2 L of denitrifying Achromobacter BP1 suspension. Denitrifying Achromobacter BP1 was adsorbed and loaded in a conical flask at a rotation speed of 150 rpm and a constant temperature of 25 °C. After static sedimentation, the supernatant was poured out and dried in an oven at 30 °C to obtain the magnetic biochar loaded functional bacteria (MBC@BP1).

4. An application of the magnetic biochar-loaded bacteria composite functional material prepared according to claim 1, 2 or 3, characterized in that: Used for removing pollutants in water and / or soil, including polycyclic aromatic hydrocarbons (PAHs) and / or heavy metals (HM); Degrade benzo[a]pyrene (BaP) and phenanthrene (Phe) in the soil, remove Cr(VI) and metabolize nitrate (NO3-); Increase soil nutrient levels, including organic matter, nitrogen and phosphorus, and improve soil microbial community diversity and structural function.

Images