A method for microbial modification of iron-based biochar for soil water retention
By performing iron modification treatment on biochar, ferrous ions are converted into iron ions by using ferrous thiobacterium oxide and loading them on the surface of biochar, the problem of complex and high cost of biochar iron modification in the prior art is solved. A significant improvement in the water retention performance of biochar has been achieved.
Patent Information
- Application Number
- CN202311345960.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-18
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2043-10-18
AI Technical Summary
In the prior art, the iron modification method of biochar is complex and costly, and it is difficult to efficiently improve the water retention performance of biochar.
Biochar is formed by pyrolyzing livestock and poultry manure rich in nitrogen-rich elements and corn stalks, and iron is added to the H2SO4 solution. After sufficient reaction, ferrous ions are converted into iron ions by using ferrous thiobacterium ferrous oxide and loading them to Iron-modified biochar is formed on the surface of biochar.
The adsorption capacity and catalytic performance of biochar are improved, and its water retention characteristics are enhanced. This method is relatively simple and reduces costs.
Smart Images
Figure CN117402624B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of biochar microbial modification, and in particular to a method for modifying iron-based biochar microbial modification for soil water retention. Background Art
[0002] Drought is a major constraint on agricultural development. Furthermore, long-term irrational farming practices and management models have led to a significant decline in farmland quality, damage to soil structure, a gradual decrease in organic matter content, reduced water and fertilizer retention capacity, and environmental pollution, severely hindering sustainable agricultural development. Currently, the use of polymers as water-retaining materials has become a new agricultural technology, achieving drought resistance, water conservation, and increased yields. However, these technologies are associated with high application costs, limited functionality, and potential environmental risks. The development of biodegradable, low-cost, and long-lasting water-retaining agents has become a major research focus.
[0003] Biochar has a promising application prospect in soil improvement due to its simple preparation method, readily available raw materials, rich pore structure, high specific surface area, and hydrophilic groups such as hydroxyl groups, carboxyl groups, and aliphatic double bonds. It can be used as a water-retaining agent. Current studies have shown that biochar modification can change its surface physicochemical properties, increase the number and types of active functional groups, increase the specific surface area, and optimize the physicochemical properties and functions of biochar. Common biochar modification methods include: 1. Alkylation modification: Biochar is modified by introducing alkylating agents into the pores of biochar to increase its hydrophilicity, surface activity, and catalytic activity; 2. Activation modification: Biochar is exposed to activators, such as alkali metal hydroxides or carbonates, to increase its porosity and surface area, improving its catalytic and adsorption properties; 3. Nanomaterial modification: Nanomaterials, such as metal oxides and carbon nanotubes, are introduced into the biochar structure to enhance its electrical conductivity, catalytic activity, and photocatalytic properties. However, the above-mentioned biochar modification methods are cumbersome to operate and have low preparation efficiency, which is not conducive to large-scale promotion. In recent years, some metal oxides such as iron and manganese have been widely used in biochar modification and have achieved good results. Common iron-based modified materials include magnetic iron oxide, nano zero-valent iron and iron-sulfur compounds. However, the preparation methods of these modified biochars are relatively complex and costly. How to efficiently modify biochar with iron is a research focus. After biochar is modified by microorganisms, it can not only balance the pH value in the soil, but also increase the content of organic carbon, soil available phosphorus, nitrate nitrogen, ammonium nitrogen, soil phosphatase and soil urease.
[0004] Therefore, those skilled in the art are committed to developing a method for microbial modification of iron-based biochar for soil water retention, which is beneficial for microorganisms to modify biochar with iron and improve the water retention performance of biochar. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method for microbial modification of iron-based biochar for soil water retention, which is beneficial for microorganisms to modify the biochar with iron and improve the water retention performance of the biochar.
[0006] The present invention solves the above technical problems with the following technical solutions: A method for microbial modification of iron-based biochar for soil water retention, comprising the following steps:
[0007] S1. Nitrogen-rich livestock and poultry manure and corn stalks were removed, washed, and dried. The treated nitrogen-rich livestock and poultry manure and corn stalks were placed in a MgCl2 solution, stirred, shaken, filtered, and dried. The mixture was then placed in an atmosphere furnace under a N2 atmosphere for pyrolysis to form biochar.
[0008] S2. placing the biochar in a H2SO4 solution and adding an iron substance, and after sufficient reaction, obtaining a modified biochar mixture containing ferrous ions;
[0009] S3. Collect acidic water samples from the coal mine drainage outlet and store them at 25°C to 30°C.
[0010] S4. Prepare liquid culture medium A: Add ammonium sulfate, potassium chloride, calcium nitrate, magnesium sulfate, and dipotassium hydrogen phosphate in a mass fraction of 3g:0.1g:0.01g:0.5g:0.5g to a reactor, add deionized water, and adjust the volume to 400 mL. Adjust the pH to 2-2.5 and sterilize.
[0011] Prepare liquid culture medium B: Dissolve 44.5 g of ferrous sulfate in distilled water and dilute to 600 mL.
[0012] After mixing liquid A and liquid B evenly, adjust the pH value to 2-2.5 to form a liquid culture medium;
[0013] S5. The liquid culture medium in step S4 and the acidic water sample in step S3 were added to the reaction vessel at a volume fraction of 10:1, and the mixture was transferred to a water bath shaker and cultured for more than 5 generations to form an enriched culture of Thiobacillus ferrooxidans;
[0014] S6. Adding the enriched Thiobacillus ferrooxidans in step S5 to the modified biochar mixture in step S2, adding ammonium sulfate solution and shaking in a water bath;
[0015] S7. Filter the mixed solution in step S6 to obtain modified biochar loaded with iron ions. After drying, place the iron-modified biochar in an atmosphere furnace and perform pyrolysis under a N2 atmosphere to obtain iron-based biochar.
[0016] The beneficial effects of the present invention are: by using ferrous iron oxidizing bacteria, ferrous ions in the solution are converted into ferric ions, so that the modified biochar is loaded with ferric ions to obtain iron-modified biochar, and the bacteria oxidize Fe 2+ Fe generated 3+ Fe content of pure chemical reagent ferric sulfate 3+ Has better oxidation ability, through bacteria to Fe 2+ 、Fe 3+ After metal ions are loaded onto the surface of biochar, the surface anion exchange capacity increases and the active adsorption sites increase significantly. The adsorption capacity and catalytic performance of the modified biochar are greatly improved. The obtained iron-modified biochar can improve the performance of biochar and improve the water retention properties of biochar.
[0017] On the basis of the above technical solution, the present invention can also be improved as follows.
[0018] Furthermore, in step S1, after the nitrogen-rich livestock and poultry manure and corn straw are put into the MgCl2 solution, the stirring time is 1h to 2h, the oscillation time is 12h to 24h, and the filtration and drying time is 2h to 3h.
[0019] The beneficial effect of adopting the above further solution is that the MgCl2 solution is conducive to the subsequent promotion of microbial activation.
[0020] Furthermore, in step S1, during the pyrolysis process of the dried nitrogen-rich livestock and poultry manure and corn straw in the atmosphere furnace, the heating rate is 5°C / min to 10°C / min, the target temperature is 300°C to 700°C, and the residence time is 1h to 2h.
[0021] The beneficial effect of adopting the above further scheme is that livestock and poultry manure rich in nitrogen and corn straw are gradually pyrolyzed under suitable conditions in an atmosphere furnace to form biochar.
[0022] Furthermore, in step S4, the pH value of the liquid culture medium A is adjusted using H2SO4 solution, and the sterilization time is 20 minutes to 30 minutes.
[0023] The beneficial effect of adopting the above further scheme is to prepare a liquid culture solution, which is conducive to the subsequent rapid cultivation of microorganisms.
[0024] Furthermore, in step S5, the culture temperature of the water bath shaker is 28° C. to 35° C., the rotation speed is 100 r / min to 120 r / min, and the culture time is 4 d to 5 d.
[0025] The beneficial effect of adopting the above further scheme is that Thiobacillus ferrooxidans is cultured under suitable conditions of a water bath shaker.
[0026] Furthermore, in step S6, the culture temperature of the water bath shaker is 28° C. to 35° C., and the culture time is 10 days to 15 days.
[0027] The beneficial effect of adopting the above further solution is to accelerate the culture rate of Thiobacillus ferrooxidans at a suitable temperature and rotation speed.
[0028] Further, in step S7, after drying, the iron-modified biochar is pyrolyzed in an atmosphere furnace with a heating rate of 5°C / min to 10°C / min, a target temperature of 300°C to 700°C, and a residence time of 1h to 2h.
[0029] The beneficial effect of adopting the above further scheme is that the iron-modified biochar is pyrolyzed to form iron-based biochar. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 The figure is a schematic flow chart of the steps of a specific embodiment of the present invention. DETAILED DESCRIPTION
[0031] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.
[0032] In the description of the present invention, it should be understood that the terms "center", "length", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "inside", "outside", "peripheral", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred system or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
[0033] In the description of the present invention, “a plurality of” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.
[0034] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.
[0035] like Figure 1 As shown, a biochar modification method, the specific implementation steps are as follows:
[0036] (1) Nitrogen-rich livestock and poultry manure and corn straw were taken separately, impurities were removed, and then washed and dried. The treated nitrogen-rich livestock and poultry manure and corn straw were mixed and placed in MgCl2 solution, stirred for 1h~2h, shaken for 12h~24h, filtered and dried for 2h~3h, and then placed in a tube furnace for pyrolysis under N2 atmosphere. The heating rate was 5℃~10℃ / min, the target temperature was 300℃~700℃, and the residence time was 1h~2h, thereby obtaining biochar.
[0037] (2) The biochar obtained in step S1 is placed in a H2SO4 solution, and iron materials such as iron wire or iron filings are added to the mixture. After sufficient reaction, a modified biochar mixture containing ferrous ions is obtained.
[0038] (3) Collect acidic water samples from the coal mine drainage outlet and store them at 25℃~30℃.
[0039] (4) Prepare liquid culture medium. Specifically, liquid culture medium A: weigh 3.0 g of ammonium sulfate, 0.1 g of potassium chloride, 0.01 g of calcium nitrate, 0.5 g of magnesium sulfate, and 0.5 g of dipotassium hydrogen phosphate into a beaker, add deionized water to fully dissolve, and adjust the volume to 400 mL; adjust the pH to 2-2.5 with sulfuric acid, and sterilize at 120°C for 20-30 min.
[0040] Solution B: Weigh 44.5g of ferrous sulfate, dissolve in distilled water, and dilute to 600mL. Sterilize. Mix Solution A and Solution B evenly and adjust the pH to 2-2.5.
[0041] (5) Enrichment and culture of Thiobacillus ferrooxidans: Specifically, take a sterilized conical flask, add 100 mL of liquid culture medium, then inoculate 10 mL of acidic water sample, transfer to a water bath shaker at 28℃~35℃ and 100r / min~120r / min and culture for 4d~5d, and the culture medium will turn from light green (Fe 2+ The color of the culture medium gradually darkened and finally turned reddish brown. The culture was stopped after 5 generations.
[0042] (6) Add 10 mL to 20 mL of the enriched Thiobacillus ferrooxidans to the modified biochar mixture containing ferrous ions, add 10 mL of 1 mol / L ammonium sulfate solution, and culture in a water bath with shaking at 28°C to 35°C for 10 to 15 days.
[0043] (7) After the cultivation is completed, the mixed solution is filtered to obtain modified biochar loaded with iron ions. After drying, the iron-modified biochar is placed in an atmosphere furnace and pyrolyzed under a N2 atmosphere. The heating rate is 5°C / min~10°C / min, the target temperature is 300°C~700°C, and the residence time is 1h~2h, thereby obtaining biochar.
[0044] The present invention provides a method for acid-modifying the biochar and reusing the acid solution, thereby avoiding waste and pollution to a certain extent. Iron wire is added to the acid solution to generate ferrous ions, which reduces the acidity of the solution and reduces the difficulty of subsequent carbon washing.
[0045] Studies have shown that bacteria oxidize Fe 2+ Fe generated 3+ Fe content of pure chemical reagent ferric sulfate 3+ Has better oxidation ability, through bacteria to Fe 2+ 、Fe 3+ After metal ions are loaded onto the surface of biochar, the anion exchange capacity of the surface increases and the active adsorption sites increase significantly. The adsorption capacity and catalytic performance of the modified biochar are greatly improved.
[0046] At a suitable temperature, the ferrous ions in the solution are converted into ferric ions by the presence of Thiobacillus ferrooxidans, which allows the modified biochar to be loaded with ferric ions, thereby obtaining iron-modified biochar. The resulting iron-modified biochar can improve the performance of the biochar and enhance its water retention properties.
[0047] The present invention is a chemoautotrophic acidophilic bacterium that can consume H + , applying iron-modified biochar loaded with Thiobacillus ferrooxidans to acidic soil can regulate the soil pH.
[0048] Example 1
[0049] (1) Nitrogen-rich livestock and poultry manure and corn straw were taken separately, impurities were removed, and then washed and dried. The treated nitrogen-rich livestock and poultry manure and corn straw were mixed and placed in MgCl2 solution. After stirring for 1 hour, oscillation was performed for 12 hours, filtration and drying were performed for 2 hours, and then placed in a tube furnace for pyrolysis under N2 atmosphere. The heating rate was 5℃ / min, the target temperature was 300℃, and the residence time was 1 hour to obtain biochar.
[0050] (2) The obtained biochar was added to a 1 mol / L sulfuric acid solution, stirred for 1 h, and then the mixture was placed in an oscillator and oscillated for 12 h to obtain an acid-modified biochar mixture.
[0051] (3) Add iron wire or iron filings to the above mixed solution and allow it to react fully to obtain a modified biochar mixed solution.
[0052] (4) Collect acidic water samples from the coal mine drainage outlet and store them at 28°C.
[0053] (5) Prepare liquid culture medium. Liquid culture medium A: Weigh 3.0 g of ammonium sulfate, 0.1 g of potassium chloride, 0.01 g of calcium nitrate, 0.5 g of magnesium sulfate, and 0.5 g of dipotassium hydrogen phosphate into a beaker. Add deionized water to fully dissolve the mixture and adjust the volume to 400 mL. Adjust the pH to 2 with sulfuric acid and sterilize at 120°C for 30 min.
[0054] Liquid medium B: Weigh 44.5 g of ferrous sulfate, dissolve in distilled water, and dilute to 600 mL. Sterilize. Mix medium A and medium B thoroughly and adjust the pH to 2.
[0055] (6) Take 3 sterilized conical flasks, add 100 mL of liquid culture medium, and then inoculate 10 mL of the initial bacterial strain (acidic water sample). Move it into a water bath shaker at 28°C to 35°C and 120 rpm and culture for 5 days. The culture medium slowly changes from the previous light green to dark reddish brown and is cultured continuously for 5 generations.
[0056] (7) Add 10 mL of enriched Thiobacillus ferrooxidans to the modified biochar mixture, add 10 mL of 1 mol / L ammonium sulfate solution, and culture in a water bath at 28°C for 15 days.
[0057] (8) After the incubation, the mixed solution was filtered to obtain modified biochar loaded with iron ions. After drying, the iron-modified biochar was placed in an atmosphere furnace and pyrolyzed under a N2 atmosphere at a heating rate of 5°C / min, a target temperature of 300°C, and a residence time of 1 h, thereby obtaining iron-modified biochar.
[0058] Example 2
[0059] (1) Nitrogen-rich livestock and poultry manure and corn straw were taken separately, impurities were removed, and then washed and dried. The treated nitrogen-rich livestock and poultry manure and corn straw were mixed and placed in a MgCl2 solution. After stirring for 1 hour, oscillation was performed for 12 hours, filtration and drying were performed for 2 hours, and then placed in a tube furnace for pyrolysis under a N2 atmosphere. The heating rate was 5℃ / min, the target temperature was 400℃, and the residence time was 1 hour. Biochar was obtained.
[0060] (2) The obtained biochar was added to a 1 mol / L sulfuric acid solution, stirred for 1 h, and then the mixture was placed in an oscillator and oscillated for 12 h to obtain an acid-modified biochar mixture.
[0061] (3) Add iron wire or iron filings to the above mixed solution and allow it to react fully to obtain a modified biochar mixed solution.
[0062] (4) Collect acidic water samples from the coal mine drainage outlet and store them at 28°C.
[0063] (5) Prepare liquid culture medium. Liquid culture medium A: Weigh 3.0 g ammonium sulfate, 0.1 g potassium chloride, 0.01 g calcium nitrate, 0.5 g magnesium sulfate, and 0.5 g dipotassium hydrogen phosphate into a beaker. Add deionized water to fully dissolve and adjust the volume to 400 mL. Adjust the pH to 2 with sulfuric acid and sterilize at 120°C for 30 min.
[0064] Liquid medium B: Weigh 44.5 g of ferrous sulfate, dissolve in distilled water, and dilute to 600 mL. Sterilize. Mix medium A and medium B thoroughly and adjust the pH to 2.
[0065] (6) Take a sterilized conical flask, add 100 mL of liquid culture medium, and then inoculate 10 mL of the initial bacterial strain (acidic water sample) in step S4. Move it into a water bath shaker at 28°C to 35°C and 120 rpm and culture for 5 days. The culture medium slowly changes from the previous light green to dark reddish brown and is cultured continuously for 5 generations.
[0066] (7) Add 10 mL of enriched Thiobacillus ferrooxidans to the modified biochar mixture, add 10 mL of 1 mol / L ammonium sulfate solution, and culture in a water bath at 28°C for 15 days.
[0067] (8) After the incubation, the mixed solution was filtered to obtain modified biochar loaded with iron ions. After drying, the iron-modified biochar was placed in an atmosphere furnace and pyrolyzed under a N2 atmosphere at a heating rate of 5°C / min, a target temperature of 400°C, and a residence time of 1 h, thereby obtaining iron-modified biochar.
[0068] Example 3
[0069] (1) Nitrogen-rich livestock and poultry manure and corn straw were taken separately, impurities were removed, and then washed and dried. The treated nitrogen-rich livestock and poultry manure and corn straw were mixed and placed in a MgCl2 solution. After stirring for 1 hour, oscillation was performed for 12 hours, filtration and drying were performed for 2 hours, and then placed in a tube furnace for pyrolysis under a N2 atmosphere. The heating rate was 5℃ / min, the target temperature was 500℃, and the residence time was 1 hour. Biochar was obtained.
[0070] (2) The obtained biochar was added to a 3 mol / L sulfuric acid solution, stirred for 1 h, and then the mixture was placed in an oscillator and oscillated for 12 h to obtain an acid-modified biochar mixture.
[0071] (3) Add iron wire or iron filings to the above mixed solution and allow it to react fully to obtain a modified biochar mixed solution.
[0072] (4) Collect acidic water samples from the coal mine drainage outlet and store them at 28°C.
[0073] (5) Prepare liquid culture medium. Liquid culture medium A: Weigh 3.0 g of ammonium sulfate, 0.1 g of potassium chloride, 0.01 g of calcium nitrate, 0.5 g of magnesium sulfate, and 0.5 g of dipotassium hydrogen phosphate into a beaker. Add deionized water to fully dissolve the mixture and adjust the volume to 400 mL. Adjust the pH to 2 with sulfuric acid and sterilize at 120°C for 30 min.
[0074] Liquid medium B: Weigh 44.5 g of ferrous sulfate, dissolve in distilled water, and dilute to 600 mL. Sterilize. Mix medium A and medium B thoroughly and adjust the pH to 2.
[0075] (6) Take a sterilized conical flask, add 100 mL of liquid culture medium, and then inoculate 10 mL of the initial bacterial strain (acidic water sample) in step S4. Move it into a water bath shaker at 28°C to 35°C and 120 rpm and culture for 5 days. The culture medium slowly changes from the previous light green to dark reddish brown and is cultured continuously for 5 generations.
[0076] (7) Add 10 mL of enriched Thiobacillus ferrooxidans to the modified biochar mixture, add 10 mL of 1 mol / L ammonium sulfate solution, and culture in a water bath at 28°C for 15 days.
[0077] (8) After the incubation, the mixed solution was filtered to obtain modified biochar loaded with iron ions. After drying, the iron-modified biochar was placed in an atmosphere furnace and pyrolyzed under a N2 atmosphere at a heating rate of 5°C / min, a target temperature of 500°C, and a residence time of 1 h, thereby obtaining biochar.
[0078] Example 4
[0079] (1) Nitrogen-rich livestock and poultry manure and corn straw were taken separately, impurities were removed, and then washed and dried. The treated nitrogen-rich livestock and poultry manure and corn straw were mixed and placed in a MgCl2 solution. After stirring for 1 hour, oscillation was performed for 12 hours, filtration and drying were performed for 2 hours, and then placed in a tube furnace for pyrolysis under a N2 atmosphere. The heating rate was 5℃ / min, the target temperature was 700℃, and the residence time was 1 hour. Biochar was obtained.
[0080] (2) The obtained biochar was added to a 3 mol / L sulfuric acid solution, stirred for 1 h, and then the mixture was placed in an oscillator and oscillated for 12 h to obtain an acid-modified biochar mixture.
[0081] (3) Add iron wire or iron filings to the above mixed solution and allow it to react fully to obtain a modified biochar mixed solution.
[0082] (4) Collect acidic water samples from the coal mine drainage outlet and store them at 28°C.
[0083] (5) Prepare liquid culture medium A: Weigh 3.0 g of ammonium sulfate, 0.1 g of potassium chloride, 0.01 g of calcium nitrate, 0.5 g of magnesium sulfate, and 0.5 g of dipotassium hydrogen phosphate into a beaker. Add deionized water to fully dissolve the mixture and adjust the volume to 400 mL. Adjust the pH to 2 with sulfuric acid and sterilize at 120°C for 30 min.
[0084] Liquid medium B: Weigh 44.5 g of ferrous sulfate, dissolve in distilled water, and dilute to 600 mL. Sterilize. Mix medium A and medium B thoroughly and adjust the pH to 2.
[0085] (6) Take a sterilized conical flask, add 100 mL of liquid culture medium, and then inoculate 10 mL of the initial bacterial strain in S4 (acidic water sample). Move it into a water bath shaker at 28°C to 35°C and 120 rpm and culture for 5 days. The culture medium slowly changes from the previous light green to dark reddish brown and is cultured continuously for 5 generations.
[0086] (7) Add 10 mL of enriched Thiobacillus ferrooxidans to the modified biochar mixture, add 10 mL of 1 mol / L ammonium sulfate solution, and culture in a water bath at 28°C for 15 days.
[0087] (8) After the incubation, the mixed solution was filtered to obtain modified biochar loaded with iron ions. After drying, the iron-modified biochar was placed in an atmosphere furnace and pyrolyzed under a N2 atmosphere at a heating rate of 5°C / min, a target temperature of 700°C, and a residence time of 1 h, thereby obtaining biochar.
[0088] Example 5
[0089] In order to understand the effect of the prepared iron-modified biochar on the water-retention properties of the soil, the following eight treatments were set up. Examples 1 to 4 and unmodified biochar were applied to the soil for a potted experiment. 800 g of soil was added to the pot, and three replicates were used for each treatment.
[0090] The processing is as follows:
[0091] T1: 800 g soil + 8 g modified biochar prepared in Example 1;
[0092] T2: 800 g soil + 8 g unmodified biochar prepared at the pyrolysis temperature of Example 1;
[0093] T3: 800 g soil + 8 g modified biochar prepared in Example 2;
[0094] T4: 800 g soil + 8 g unmodified biochar prepared at the pyrolysis temperature of Example 2;
[0095] T5: 800 g soil + 8 g modified biochar prepared in Example 3;
[0096] T6: 800 g soil + 8 g unmodified biochar prepared at the pyrolysis temperature of Example 3;
[0097] T7: 800 g soil + 8 g modified biochar prepared in Example 4;
[0098] T8: 800 g soil + 8 g unmodified biochar prepared at the pyrolysis temperature of Example 4;
[0099] After placing soil and biochar into pots, cucumbers were planted and watered with 200 mL every five days. When the plants reached a height of about 15 cm, soil samples were collected to determine the porosity and water content of the soil and the fresh weight of the plants. The results are shown in Table 1.
[0100] Adding the iron-modified biochar prepared by the present invention to soil improved the soil's physical structure. Compared with unmodified biochar, the soil's bulk density decreased by 2.46% to 11.29%, the total porosity increased by 8.16% to 10.27%, and the capillary porosity increased by 5.84% to 10.23%.
[0101] Adding the iron-modified biochar prepared in this invention to soil enhanced its water-holding capacity. Compared to unmodified biochar, soil moisture content increased by 25.75% to 33.40%, saturated water content increased by 13.43% to 16.28%, and plant fresh weight increased by 17.41% to 26.70%. Compared to unmodified biochar, soil treated with iron-modified biochar exhibited a stronger water-holding capacity.
[0102] Table 1 Physical and chemical properties of soil under each treatment
[0103]
[0104] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.
[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A method for microbial modification of iron-based biochar for soil water retention, characterized in that: The following steps are involved: S1. Remove impurities from nitrogen-rich livestock and poultry manure and corn stalks, wash and dry them, and place the treated nitrogen-rich livestock and poultry manure and corn stalks into a MgCl2 solution, stir and vibrate, filter and dry them, and place them into an atmosphere furnace for pyrolysis in a N2 atmosphere to form biochar; During the pyrolysis process of the dried nitrogen-rich livestock and poultry manure and corn straw in the atmosphere furnace, the heating rate is 5℃ / min~10℃ / min, the target temperature is 300℃~700℃, and the residence time is 1h~2h; S2. placing the biochar in a H2SO4 solution and adding an iron substance, and obtaining a modified biochar mixed solution containing ferrous ions after sufficient reaction; S3. Collect acidic water samples from the coal mine drainage outlet and store them at 25℃~30℃; S4. Prepare liquid culture medium A: add ammonium sulfate, potassium chloride, calcium nitrate, magnesium sulfate, and potassium dihydrogen phosphate into the reactor according to the mass fraction of 3g:0.1g:0.01g:0.5g:0.5g, add deionized water and adjust the volume to 400mL, adjust the pH value to 2-2.5, and sterilize; Prepare liquid culture medium B: dissolve 44.5 g of ferrous sulfate in distilled water and make up to 600 mL; After mixing liquid A and liquid B evenly, adjust the pH value to 2-2.5 to form a liquid culture medium; S5. The liquid culture medium in step S4 and the acidic water sample collected in step S3 are added to the reaction vessel at a volume fraction of 10:1, and the mixture is transferred to a water bath oscillator and cultured for more than 5 generations to form an enriched culture of Thiobacillus ferrooxidans; S6. Adding the enriched Thiobacillus ferrooxidans in step S5 to the modified biochar mixture in step S2, adding ammonium sulfate solution and culturing in a water bath with shaking; The incubation temperature of the water bath shaker is 28℃~35℃, and the incubation time is 10d~15d; S7. Filter the mixed solution in step S6 to obtain modified biochar loaded with iron ions, and after drying, place the iron-modified biochar in an atmosphere furnace and perform pyrolysis under a N2 atmosphere to obtain iron-based biochar; After drying, the iron-modified biochar is pyrolyzed in an atmosphere furnace with a heating rate of 5°C / min to 10°C / min, a target temperature of 300°C to 700°C, and a residence time of 1h to 2h.
2. The method for microbial modification of iron-based biochar for soil water retention according to claim 1, characterized in that: In step S1, after the livestock and poultry manure and corn stalks rich in nitrogen are put into the MgCl2 solution, the stirring time is 1h to 2h, the oscillation time is 12h to 24h, and the filtering and drying time is 2h to 3h.
3. The method for microbial modification of iron-based biochar for soil water retention according to claim 1, characterized in that: In step S4, the pH value of the liquid culture medium A is adjusted using H2SO4 solution, and the sterilization time is 20 min to 30 min.
4. The method for microbial modification of iron-based biochar for soil water retention according to claim 1, characterized in that: In step S5, the culture temperature of the water bath shaker is 28°C to 35°C, the rotation speed is 100 r / min to 120 r / min, and the culture time is 4 d to 5 d.