A biochar material and its preparation method

Abstract

This invention relates to the field of biochar materials for environmental remediation, and discloses a biochar material and its preparation method. The preparation method of the biochar material includes the following steps: Step 1: Using sesame meal as a precursor, the sesame meal is pulverized and sieved for later use; Step 2: The sesame meal obtained in Step 1 is placed in a heating device, heated to 900℃ under a nitrogen atmosphere, kept at that temperature, and then naturally cooled to room temperature for later use. The biochar material prepared by this invention has high suspension performance. The biochar slurry with a concentration between 3.0 and 7.0 g / L achieves a relatively stable suspension state, with the most stable suspension effect in the concentration range of 3.0-7.0 g / L. The biochar material prepared by this invention has high catalytic activation performance against the oxidant persulfate, and the system formed by the combination with persulfate has a high degradation effect on dichloroethane, a common organic pollutant in groundwater, in the form of an in-situ reaction zone.

Description

Technical Field

[0001] This invention relates to the field of biochar materials technology, and in particular to a biochar material and its preparation method. Background Technology

[0002] Oil extraction and refining, pipeline leaks, and excessive pesticide spraying can cause organic pollution in groundwater. In-situ remediation of contaminated areas requires the use of in-situ reaction zones. This method minimizes the impact on the ecological environment of the contaminated area and requires minimal construction work. However, existing remediation materials, such as biochar, suffer from poor suspension and low catalytic activation performance. The former causes significant disturbance to the underground environment of the remediation area, while the latter cannot effectively degrade the target pollutants. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a biochar material and its preparation method.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for preparing biochar material includes the following steps:

[0006] Step 1: Using sesame meal as a precursor, pulverize the sesame meal and sieve it for later use;

[0007] Step 2: Place the sesame meal obtained in Step 1 into a heating device, heat it to 900℃ under a nitrogen atmosphere, keep it at that temperature for 180 minutes, and then let it cool naturally to room temperature for later use.

[0008] Step 3: Wash the product obtained in Step 2 three times with dilute hydrochloric acid and sodium hydroxide alternately, and then wash it with ethanol and deionized water alternately until it is neutral.

[0009] Step 4: Mix urea and the product obtained in Step 3 at a mass ratio of 1:5, and then perform ball milling.

[0010] Step 5: Place the product obtained in Step 4 into a heating device, heat it to 300°C under a nitrogen atmosphere, keep it at that temperature for 180 minutes, and then let it cool naturally to room temperature for later use.

[0011] Step 6: Prepare the product obtained in Step 5 into a suspension, and after ultrasonic vibration, obtain a biochar material with high suspension and high catalytic activation performance.

[0012] Preferably, in step 2, the heating rate is 5℃ / min.

[0013] Preferably, in step 3, the concentration of dilute hydrochloric acid is 10% and the concentration of sodium hydroxide is 10%.

[0014] Preferably, in step 4, the ball milling time is 60 minutes.

[0015] Preferably, in step 5, the heating rate is 10℃ / min.

[0016] Preferably, in step 6, the duration of ultrasonic oscillation is 120 minutes.

[0017] A biochar material prepared by the above-described method for preparing a biochar material.

[0018] The beneficial effects of this invention are as follows:

[0019] The biochar material prepared by this invention has high suspension performance. The suspension time and suspension conditions vary at different concentrations. In biochar slurries with concentrations between 3.0 and 7.0 g / L, the distance between particles just meets the effective range of repulsion, achieving a relatively stable suspension state. Further increasing the concentration shortens the distance between particles, breaks through the potential energy trap, and accelerates the settling speed of the biochar particles. Therefore, the biochar slurry concentration range with the most stable suspension effect is 3.0-7.0 g / L. The biochar material prepared by this invention has high catalytic activation performance for the oxidant persulfate. The system formed by combining biochar and persulfate has a high degradation effect on dichloroethane, a common organic pollutant in groundwater. The optimal addition ratio of the system is that for every 1 g of biochar added, only 2.5 mM persulfate is needed to achieve an effective degradation effect. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the suspension effect of biochar slurry of different concentrations after standing for 210 days.

[0021] Figure 2 A schematic diagram showing the Zeta potential of biochar slurries with different particle sizes at different initial concentrations;

[0022] Figure 3 This diagram illustrates the effect of the system on the degradation of dichloroethane at different initial concentrations. The left side of the diagram represents only physical adsorption, while the right side represents oxidative degradation.

[0023] Figure 4 A schematic diagram of the paramagnetic resonance test results of a singlet oxygen signal source system;

[0024] Figure 5 Schematic diagram of paramagnetic resonance test results for the superoxide radical signal source system;

[0025] Figure 6 Schematic diagram of paramagnetic resonance test results for the hydroxyl radical and sulfate radical signal source system;

[0026] Figure 7 This is a BET characterization graph;

[0027] Figure 8 FT-IR characterization plot;

[0028] Figure 9 XPS characterization plot;

[0029] Figure 10 This is a SEM image of the biochar material. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] A method for preparing biochar material includes the following steps:

[0032] Step 1: Using sesame meal as a precursor, pulverize the sesame meal and sieve it for later use;

[0033] Step 2: Place the sesame meal obtained in Step 1 into a heating device, and heat it to 900℃ at a heating rate of 5℃ / min under a nitrogen atmosphere. After holding it at this temperature for 180 minutes, allow it to cool naturally to room temperature for later use.

[0034] Step 3: After washing the product obtained in Step 2 three times with 10% dilute hydrochloric acid and 10% sodium hydroxide, wash it with ethanol and deionized water alternately until it is neutral.

[0035] Step 4: Mix urea and the product obtained in step 3 at a mass ratio of 1:5, and then ball mill for 60 minutes;

[0036] Step 5: Place the product obtained in Step 4 into a heating device, and heat it to 300°C at a heating rate of 10°C / min under a nitrogen atmosphere. Hold it at this temperature for 180 minutes, and then allow it to cool naturally to room temperature for later use.

[0037] Step 6: Prepare the product obtained in Step 5 into a suspension, and after ultrasonic vibration for 120 minutes, a biochar material with high suspension and high catalytic activation performance is obtained.

[0038] A biochar material prepared by the above-described method for preparing a biochar material.

[0039] The biochar material prepared by this invention has high suspension performance; the suspension time and suspension characteristics vary at different concentrations, as shown in the figure. Figure 1 See [link to Zeta point data for suspensions of different concentrations] Figure 2 .

[0040] The suspension mechanism of the biochar material prepared in this invention is analyzed as follows: Taking biochar with a particle size of 75 μm as an example, although the zeta potential of biochar slurry below 1.0 g / L is high, the low concentration results in a large distance between biochar particles, rendering the mutual repulsion between particles ineffective. However, in biochar slurry with a concentration between 3.0 and 7.0 g / L, the distance between particles just meets the effective range of repulsion, achieving a relatively stable suspension state. Further increasing the concentration shortens the distance between particles, breaks through the potential energy trap, and accelerates the settling speed of the biochar particles. Therefore, the concentration range of the biochar material slurry with the most stable suspension effect is 3.0-7.0 g / L.

[0041] Using the Python programming language and the GradientBoostingRegressor model from the Scikit-learn library, linear regression was performed to fit the suspension effect of biochar in different systems, showing the suspension effect under different particle sizes, concentrations, and time conditions.

[0042] The biochar material prepared by this invention has high catalytic activation performance for the oxidant persulfate. The system formed by combining it with persulfate has a high degradation effect on dichloroethane, a common organic pollutant in groundwater. The optimal addition ratio of the system is that for every 1g of biochar added, only 2.5mM of persulfate needs to be added to achieve an effective degradation effect.

[0043] The degradation mechanism of the system formed by the biochar material prepared in this invention and combined with persulfate is as follows: the system is based on advanced oxidation technology, with carbon activating persulfate as the mechanism, generating active oxygen species ·OH. 1 O2, SO4· - and O2 - ( Figure 4-6 It oxidizes and degrades pollutants, eventually mineralizing dichloroethane into carbon dioxide and water.

[0044] The biochar material prepared in this invention is a green, economical, and efficient environmental remediation material made from agricultural waste sesame meal for the purpose of in-situ groundwater remediation. Due to organic pollution of groundwater caused by oil extraction and refining, pipeline leaks, and excessive pesticide spraying, the system remediates the polluted area in the form of an in-situ reaction zone. Throughout the remediation process, the injected biochar material does not cause significant disturbance to the underground environment, does not clog the groundwater environment, does not change the groundwater level or flow direction, and requires no large-scale excavation. Only shallow wells need to be drilled according to the size of the polluted area to inject the biochar material and reagents.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method of producing a biochar material, characterized by, The method comprises the following steps: Step 1: taking sesame meal as a preparation precursor, crushing the sesame meal, and sieving for use; Step 2: placing the sesame meal obtained in step 1 into a heating device, heating to 900 DEG C under a nitrogen atmosphere, keeping for 180 min, and then naturally cooling to room temperature for use; Step 3: using dilute hydrochloric acid and sodium hydroxide to alternately clean the product obtained in step 2 for three times, and then using ethanol and deionized water to alternately clean until neutral; Step 4: mixing urea and the product obtained in step 3 according to a mass ratio of 1:5, and then performing ball milling treatment; Step 5: placing the product obtained in step 4 into a heating device, heating to 300 DEG C under a nitrogen atmosphere, keeping for 180 min, and then naturally cooling to room temperature for use; Step 6: configuring the product obtained in step 5 into a suspension, and then obtaining a biochar material with high suspension and high catalytic activation performance and a concentration range of 3.0-7.0 g / L.

2. The method of claim 1, wherein the biochar material is prepared by pyrolysis of a biomass material. In step 2, the heating rate is 5 DEG C / min.

3. The method of claim 1, wherein the biochar material is prepared by: In step 3, the concentration of dilute hydrochloric acid is 10%, and the concentration of sodium hydroxide is 10%.

4. The method of claim 1, wherein the biochar material is prepared by: In step 4, the ball milling time is 60 min.

5. The method of claim 1, wherein the biochar material is prepared by: In step 5, the heating rate is 10 DEG C / min.

6. The method of claim 1, wherein the biochar material is prepared by: In step 6, the ultrasonic oscillation time is 120 min.

7. A biochar material, characterized in that, The biochar material is prepared by the preparation method of any one of claims 1-6.

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