Preparation method of biochar for repairing soil organic matter pollution

Abstract

The invention provides a preparation method of biochar for repairing soil organic matter pollution, and relates to the technical field of soil repairing. The biochar is prepared from coconut shells soaked in a treating fluid and mushroom bran according to the mass ratio of 1: (2-4), the treating fluid is prepared by mixing laccase and a phosphate buffer solution at 30-44 DEG C according to the volume ratio of 1: 100, and the preparation method of the biochar comprises the following steps: preparing the following raw materials: the coconut shells and the mushroom bran; the preparation method comprises the following steps: cleaning and drying coconut shells, soaking the coconut shells in a treating fluid for 4-6 hours, taking out, cleaning, drying, crushing and sieving to obtain coconut shell powder for later use; the coconut shells and the mushroom residues are mixed to serve as the biochar to adsorb soil organic pollution, the effective adsorption capacity is guaranteed, meanwhile, an environment-friendly and economical utilization method of the coconut shells and the mushroom residues is developed, the cost of the biochar is reduced, the coconut shells are soaked in the treating fluid in advance, the ageing resistance of the coconut shells is enhanced, and the application value of the biochar is comprehensively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biochar preparation, in particular to a biochar preparation method for repairing soil organic matter pollution. BACKGROUND

[0002] With the acceleration of agricultural intensification in China, the application range and dosage of herbicides show a significant growth trend, and as the main food crop, rice is the first to be affected - the annual herbicide input in its planting area has reached 23,000 tons. In the tobacco-rice rotation system in the south, long-term application of commonly used herbicides such as sulfonylurea (such as nicosulfuron) has intensified the cumulative effect of soil residues, resulting in a high proportion of 12-18% of tobacco plants showing symptoms of drug damage such as deformity, growth inhibition, and leaf spot.

[0003] Under this background, biochar is considered as a potential remediation material to alleviate the toxicity of herbicide residues due to its unique porous structure, but the adsorption effect of single biochar system is limited, and biochar will age after a certain period, reducing the adsorption capacity and failing to maintain long-term adsorption effect. SUMMARY

[0004] To achieve the above purpose, the present application is realized by the following technical scheme: a biochar preparation method for repairing soil organic matter pollution, the biochar is prepared from coconut shells soaked in a treatment solution and spent mushroom substrate in a mass ratio of 1:2-4; The treatment solution is prepared by mixing laccase and phosphate buffer solution at a volume ratio of 1:100 at 30-44℃.

[0005] Preferably, the laccase activity is 50,000 U / g, and the phosphate buffer solution pH is 5.0.

[0006] Preferably, the preparation method of the biochar comprises the following steps: S1, prepare the raw materials according to the following weight parts: coconut shells 10-20 parts, spent mushroom substrate 20-80 parts; S2, wash and dry the coconut shells, then soak them in the treatment solution for 4-6 hours, take them out, wash and dry them, crush and sieve them to obtain coconut shell powder for standby; S3, wash and dry the spent mushroom substrate, crush and sieve it to obtain spent mushroom substrate powder for standby; S4, mix the treated coconut shell powder and the spent mushroom substrate powder to obtain a mixture; S5, place the mixture in a tube furnace under N2 environment, heat it to 400-600℃ at a heating rate of 10-20℃ / min, keep it at this temperature for 100-140min, then heat it to 850-950℃ at a heating rate of 5-15℃ / min, keep it at this temperature for 2-3h, and cool it to room temperature to obtain the biochar.

[0007] Preferably, the drying condition of the coconut shell in the step S2 is 120℃ for 2h, and the drying temperature after soaking is 100-150℃ for 6-8h.

[0008] Preferably, the drying temperature of the fungus chaff in the step S3 is 40-80℃ for 2-4h.

[0009] Preferably, the sieving in the steps S2 and S3 is through 60-80 mesh sieve.

[0010] Preferably, the stirring in the step S4 is at a speed of 800-1000r / min for 20-30min, and the aluminum foil is used to seal the opening to prevent mass loss during the stirring.

[0011] The present application provides a method for preparing biochar for repairing soil organic pollution, which has the following advantages compared with the prior art: The present application uses coconut shell and fungus chaff to mix and prepare biochar for adsorbing soil organic pollution, which ensures effective adsorption force, develops an environmentally friendly and economic utilization method of coconut shell and fungus chaff, reduces the cost of biochar, and enhances the anti-aging property of the coconut shell by pre-soaking in the treatment liquid, thereby improving the application value of the biochar. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The figure shows the change of the adsorption rate of herbicide with time for the sample biochar prepared for the blank soil, the example and the comparative example; Figure 2 The figure shows the change of the adsorption rate of herbicide with time for the sample biochar prepared for the blank soil, the example and the comparative example after aging; DETAILED DESCRIPTION

[0013] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application is described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0014] The laccase was purchased from Pombio Biology, and the enzyme activity was 50000U / g. The phosphate buffer was purchased from Guangjian Detection Technology Co., Ltd., and the pH was 5.0.

[0015] Embodiment: Preparation of biochar: Biochar A: S1, the following weight parts of raw materials were prepared: coconut shell 10 parts, fungus chaff 20 parts; S2, take the washed and dried at 120℃ for 2h coconut shell in excess of the treatment solution (mixed by laccase and phosphate buffer solution at 37℃ according to the volume ratio of 1:100) for 5h, take out, wash and dry at 120℃ and continue for 7h, crush through 70 mesh sieve, get coconut shell powder, ready for use; S3, take the washed and dried at 60℃ for 3h rice bran, crush through 70 mesh sieve, get rice bran powder, ready for use; S4, take the treated coconut shell powder and rice bran powder, stir and mix, get the mixture; S5, in N2 environment, put the mixture in the tube furnace, heat to 500℃ at the heating rate of 15℃ / min, keep for 120min, then heat to 900℃ at the heating rate of 10℃ / min, keep pyrolysis for 2.5h, cool to room temperature, get the biochar.

[0016] Biochar B: The preparation of biochar B refers to the preparation method of biochar A, only S1 is different, the rest steps are the same, specifically: S1, prepare the raw materials according to the following weight parts: coconut shell 20 parts, rice bran 80 parts; Comparative example: For the preparation method of biochar A in the example, selective adjustment is made, such as: using unsoaked coconut shell, adjusting the pyrolysis temperature or replacing with single composition, the rest are the same as the preparation steps of biochar A in the example, specifically: Biochar C: The preparation of biochar C refers to the preparation method of biochar A, only S2 is different, the rest steps are the same, specifically: S2, take the washed and dried at 120℃ for 2h coconut shell, crush through 70 mesh sieve, get coconut shell powder, ready for use; Biochar D: The preparation of biochar D refers to the preparation method of biochar A, only S5 is different, the rest steps are the same, specifically: S5, in N2 environment, put the mixture in the tube furnace, heat to 900℃ at the heating rate of 10℃ / min, keep pyrolysis for 2.5h, cool to room temperature, get the biochar.

[0017] Biochar E: S1, prepare the raw materials according to the following weight parts: coconut shell powder 15 parts; S2, take the washed and dried at 120℃ for 2h coconut shell, soak in excess of the treatment solution (mixed by laccase and phosphate buffer solution at 37℃ according to the volume ratio of 1:100) for 5h, take out, wash and dry at 120℃ and continue for 7h, crush through 70 mesh sieve, get coconut shell powder, ready for use; S3, under N2 environment, the coconut shell powder was placed in a tube furnace and heated to 500℃ at a heating rate of 15℃ / min, kept for 120min, then heated to 900℃ at a heating rate of 10℃ / min, kept for pyrolysis for 2.5h, cooled to room temperature, to obtain biochar.

[0018] Biochar F: S1, the following raw materials were prepared according to the weight parts: mushroom dregs powder 45 parts; S2, the mushroom dregs were washed, dried at 60℃ for 3h, and crushed through a 70 mesh sieve to obtain mushroom dregs powder, which was used as prepared. S3, under N2 environment, the mushroom dregs powder was placed in a tube furnace and heated to 500℃ at a heating rate of 15℃ / min, kept for 120min, then heated to 900℃ at a heating rate of 10℃ / min, kept for pyrolysis for 2.5h, cooled to room temperature, to obtain biochar.

[0019] Detection: The blank soil was set as a control group; the sample biochar was prepared according to the steps of the examples and comparative examples.

[0020] 1, detection of the adsorption of biochar to herbicides: In a 50mL polypropylene centrifuge tube, 0.98g soil was mixed with 20mg sample biochar (2% w / w), 10mL background solution containing 1mg / L nicosulfuron (0.01M CaCl2, 0.5% NaN3 as microbial inhibitor) was added, 0.1ml NaOH was used to adjust the pH to 6.5±0.2 to simulate the farmland environment, and then sealed and placed in a constant temperature shaking incubator (25±0.5℃, 120rpm) for dynamic adsorption. Samples were taken at 8h, 24h, 48h, 72h and 168h, respectively, and immediately centrifuged at 5000xg for 30min to terminate the reaction. The supernatant was filtered through a 0.22μm nylon membrane, and then quantitatively analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS / MS, AB Sciex 4500QTRAP). All experiments were set in triplicate, and the results are shown in Table 1 and Figure 1 Table 1 ​From the above table, the blank soil has a certain adsorption capacity for herbicide, but the adsorption rate is relatively slow, which may mainly depend on the physical adsorption of the soil itself. Although the adsorption rate of biochar A and biochar B is similar to that of the blank soil in the early stage, the adsorption rate is faster than that of the blank soil with the extension of time, and it has a great advantage in 168h. Although the adsorption rate of biochar E in the early stage is not much different from that of example 1, the adsorption rate slows down significantly after 48h with the increase of time, and the adsorption rate is larger than that of example 1 in 168h. The adsorption rate of biochar F increases greatly between 8h and 24h, but its adsorption capacity is still less than that of example 1 or example 2, that is, the biochar of example 1 can produce better effect on the soil polluted by herbicide.

[0021] 2. Anti-aging detection of biochar The sample biochar was immersed in a 15% H2O2 solution, heated in a water bath at 80℃, and reacted for 6 hours. After the reaction, the sample was washed with pure water to remove residual H2O2, and the washed sample was dried at 105℃. The change in adsorption performance of the biochar before and after aging was evaluated, and the results are shown in Table 2 and Figure 2 Table 2 From the above table, the adsorption capacity of the example after aging fluctuates little, while the adsorption rate of biochar C before aging (as shown in Table 1) and after aging decreases more, that is, the anti-aging effect of the sample biochar prepared by biochar A is better.

[0022] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.​

Claims

1. A method for producing biochar for remediating soil organic contamination, characterized by, The biochar is prepared from coconut shell soaked in treatment solution and fungus dregs in a mass ratio of 1:2-4. The treatment solution is prepared by mixing laccase and phosphate buffer solution in a volume ratio of 1:100 at 30-44℃.

2. The production method according to claim 1, characterized by, The laccase activity is 50000 U / g, and the phosphate buffer solution has a pH of 5.

0.

3. The production method according to claim 1, characterized by, The preparation method of the biochar comprises the following steps: S1, preparing raw materials according to the following weight parts: coconut shell 10-20 parts, fungus dregs 20-80 parts; S2, washing and drying the coconut shell, then soaking in the treatment solution for 4-6 h, washing and drying after taking out, crushing and sieving to obtain coconut shell powder for standby; S3, washing and drying the fungus dregs, crushing and sieving to obtain fungus dregs powder for standby; S4, mixing the treated coconut shell powder and fungus dregs powder to obtain a mixture; S5, placing the mixture in a tube furnace under N2 environment, heating to 400-600℃ at a heating rate of 10-20℃ / min, keeping for 100-140 min, then heating to 850-950℃ at a heating rate of 5-15℃ / min, keeping for 2-3 h for pyrolysis, cooling to room temperature to obtain the biochar.

4. The production method according to claim 3, characterized by, In the step S2, the drying condition of the coconut shell is 120℃ for 2 h, and the drying temperature after soaking is 100-150℃ for 6-8 h.

5. The preparation method according to claim 3, characterized in that, In the step S3, the drying temperature of the fungus dregs is 40-80℃ for 2-4 h.

6. The preparation method according to claim 3, characterized in that, In the steps S2 and S3, the sieving is through 60-80 mesh sieve.

7. The preparation method according to claim 3, characterized in that, In the step S4, the stirring is at a speed of 800-1000 r / min for 20-30 min, and the stirring process is sealed with aluminum foil to prevent mass loss.

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