Acid-washed modified lobster shell biochar and preparation method and application thereof

Abstract

This invention belongs to the field of adsorption material preparation technology, specifically relating to an acid-washed modified lobster shell biochar, its preparation method, and its application. The present invention uses acid washing to remove inorganic components from biomass, creating larger pores within the biomass. These larger pores then collapse in the biochar, forming smaller pores. This increases the specific surface area and total pore volume of the modified biochar, providing more adsorption sites for lead ions and pharmacopherol (PHE), significantly improving the adsorption efficiency of the biochar for these pollutants. The acid washing modification also lowers the H / C atomic ratio of the biochar, enhancing its aromaticity and deepening its aromatization. This promotes the interaction between lead ions and π electrons, as well as the π-π conjugation of PHE, further enhancing the adsorption effect. Finally, the acid washing modification reduces the hydrophilicity of the biochar, making it more suitable for adsorbing non-polar pollutants.

Description

Technical Field

[0001] This invention belongs to the field of adsorption material preparation technology, specifically relating to an acid-washed modified lobster shell biochar, its preparation method, and its application. Background Technology

[0002] The development of industries such as lead-acid batteries has led to a significant increase in lead (Pb) consumption. However, during production and use, large amounts of lead accumulate in the soil, affecting its function and properties. Yunnan Province is rich in mineral resources, and long-term mining and smelting have also caused serious soil pollution. Furthermore, heavy metals in the soil can be absorbed by the human body through ecological cycles and the food chain, posing a serious threat to human health. Therefore, the remediation of heavy metal-contaminated soil is urgently needed.

[0003] Polycyclic aromatic hydrocarbons (PAHs) are typical persistent organic pollutants. When they enter the soil, they affect the composition and structure of soil microbial communities and pose a threat to human and animal health after entering the food chain. Phenanthrene (PHE) is a typical PAH, exhibiting high chemical stability, being difficult to degrade, and possessing high ecotoxicity.

[0004] Biochar is a soil amendment material with strong adsorption capacity. Due to its large specific surface area and well-developed pore structure, biochar has potential for adsorbing heavy metals and organic pollutants; however, current biochar technologies do not show good adsorption performance for pollutants. Summary of the Invention

[0005] The purpose of this invention is to provide an acid-washed modified lobster shell biochar, its preparation method, and its application. The acid-washed modified lobster shell biochar provided by this invention has good adsorption performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides an acid-washed modified lobster shell biochar with a specific surface area of ​​not less than 33 m². 2 ·g -1 The total pore volume is not less than 0.1 cm³. 3 ·g -1 The total volume of the micropores is not less than 0.014 cm³. 3 ·g -1 .

[0008] Preferably, the particle size of the acid-washed modified lobster shell biochar is 145–165 μm;

[0009] The acid-washed modified lobster shell biochar has pore sizes including micropores, mesopores, and macropores; the micropores have a diameter of 0.5–1.8 nm; the mesopores have a diameter of 2–50 nm; and the macropores have a diameter of 50–200 nm, excluding 50 nm.

[0010] This invention also provides a method for preparing the acid-washed modified lobster shell biochar described above, comprising the following steps:

[0011] (1) Lobster shell particles are mixed with HF-HCl mixed acid solution and acid washed to obtain acid-washed modified material; the mixed acid washing includes sequential shaking modification and solid-liquid separation; the mixed acid washing is performed no less than once;

[0012] (2) The acid-washed modified material is washed with water until neutral and then pyrolyzed to obtain acid-washed modified lobster shell biochar; the pyrolysis is carried out under oxygen-limited conditions.

[0013] Preferably, the solid-liquid ratio of the lobster shell particles and the HF-HCl mixed acid solution is 1g:(5-10)mL.

[0014] Preferably, the lobster shell particles have a particle size of 290–840 micrometers; the volume fraction of HF in the HF-HCl mixed acid solution is 10–10.2%; and the volume fraction of HCl in the HF-HCl mixed acid solution is 8.3–8.5%.

[0015] Preferably, the pyrolysis temperature is 300±2℃ or 600±2℃, and the holding time is 2h.

[0016] Preferably, the heating rate of the pyrolysis is 8-10 °C / min.

[0017] Preferably, the time for a single oscillation modification is 1.5 to 2 hours, and the time for a single solid-liquid separation is 12 to 15 minutes.

[0018] Preferably, the solid-liquid separation is performed by centrifugation; the centrifugation speed is 3800-4000 rpm and the time is 12-15 min.

[0019] This invention also provides the application of the acid-washed modified lobster shell biochar described in the above-described scheme or the acid-washed modified lobster shell biochar prepared by the above-described scheme in the remediation of heavy metal contaminated soil, polycyclic aromatic hydrocarbon contaminated soil and heavy metal-polycyclic aromatic hydrocarbon complex contaminated soil.

[0020] This invention provides an acid-washed modified lobster shell biochar. The acid washing process removes inorganic components from the biomass, creating larger pores. These larger pores then collapse in the biochar, forming smaller pores. This increases the specific surface area and total pore volume of the modified biochar, thereby increasing its potential for Pb production. 2+ PHE provides more adsorption sites, significantly improving the adsorption capacity of biochar for Pb. 2+The adsorption effect of PHE. This invention, through acid washing modification, reduces the H / C atomic ratio of biochar, thereby enhancing the aromaticity of the biochar, deepening the aromatization, and promoting Pb adsorption. 2+ The interaction with π electrons also promotes the π-π conjugation of PHE, thus enhancing the adsorption effect. This invention, through acid washing modification, reduces the hydrophilicity of biochar, making it more suitable for adsorbing non-polar pollutants.

[0021] The acid-washed modified lobster shell biochar provided by this invention adsorbs Pb 2+ Heavy metal ions are mainly produced through chemical adsorption, complexation, and Pb. 2+ The adsorption mechanisms for heavy metal ions include coordination with π electrons, while the adsorption of polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene (PHE) mainly involves surface adsorption, π-π electron donor-acceptor interactions, and hydrogen bonding. Therefore, the acid-washed modified lobster shell biochar provided by this invention exhibits excellent adsorption effects on pollutants such as heavy metal ions and PAHs, and is of great significance for the remediation of soils contaminated with combined heavy metal and PAH pollution.

[0022] This invention also provides a method for preparing acid-washed modified lobster shell biochar as described above. Lobsters, as aquatic animals, currently have limited resource utilization of their shells. This invention prepares lobster shell biochar from lobster shells, utilizing readily available and low-cost raw materials, achieving resource utilization through "waste treatment." The preparation method provided by this invention is simple, easy to operate, has a short reaction time, and is easy to promote and apply.

[0023] This invention also provides the application of the acid-washed modified lobster shell biochar described in the above-described scheme or the acid-washed modified lobster shell biochar prepared by the above-described method in the remediation of heavy metal contaminated soil, polycyclic aromatic hydrocarbon (PAH) contaminated soil, and heavy metal-PAH complex contaminated soil. The acid-washed modified lobster shell biochar provided by this invention exhibits excellent adsorption effects on heavy metal ions or non-polar pollutants, and is particularly suitable for the adsorption of lead ions and PAHs such as phenanthrene, which is of great significance for the remediation of heavy metal-PAH complex contaminated soil. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a SEM image of the modified lobster shell biochar prepared in Example 1 of the present invention;

[0026] Figure 2This is a SEM image of the modified lobster shell biochar prepared in Example 2 of the present invention;

[0027] Figure 3 SEM image of the lobster shell biochar prepared in Comparative Example 1 of this invention.

[0028] Figure 4 This is a SEM image of the lobster shell biochar prepared in Comparative Example 2 of this invention.

[0029] Figure 5 These are adsorption isotherm diagrams obtained from test examples 1 to 3 of the present invention;

[0030] Figure 6 The adsorption isotherms obtained from test examples 4 to 5 of this invention are shown. Detailed Implementation

[0031] This invention provides an acid-washed modified lobster shell biochar with a specific surface area of ​​not less than 33 m². 2 ·g -1 The total pore volume is not less than 0.1 cm³. 3 ·g -1 The total volume of the micropores is not less than 0.014 cm³. 3 ·g -1 .

[0032] In this invention, the particle size of the acid-washed modified lobster shell biochar is preferably 145–165 μm, more preferably 148–162 μm, and even more preferably 150–160 μm; the pore size of the acid-washed modified lobster shell biochar preferably includes micropores, mesopores, and macropores; the pore size of the micropores is preferably 0.5–1.8 nm, more preferably 0.6–0.8 nm; the pore size of the mesopores is preferably 2–50 nm, more preferably 3.5–10 nm; and the pore size of the macropores is preferably 50–200 nm (excluding 50 nm), more preferably 50–100 nm (excluding 50 nm). The acid-washed modified lobster shell biochar provided by this invention has a large specific surface area and broad application prospects in the field of adsorption.

[0033] This invention also provides a method for preparing the acid-washed modified lobster shell biochar described above, comprising the following steps:

[0034] (1) Lobster shell particles are mixed with HF-HCl mixed acid solution and acid washed to obtain acid-washed modified material; the mixed acid washing includes sequential shaking modification and solid-liquid separation; the mixed acid washing is performed no less than once;

[0035] (2) The acid-washed modified material is washed with water until neutral and then pyrolyzed to obtain acid-washed modified lobster shell biochar; the pyrolysis is carried out under oxygen-limited conditions.

[0036] This invention involves acid washing lobster shell particles with HF-HCl mixed acid solution to obtain an acid-modified product. In this invention, the solid-liquid ratio of the lobster shell particles to the HF-HCl mixed acid solution is preferably 1g:(5-10)mL, more preferably 1g:(6-9)mL, and even more preferably 1g:(7-8)mL.

[0037] In this invention, the particle size of the lobster shell particles is preferably 290-840 micrometers, more preferably 310-790 micrometers, and even more preferably 440-640 micrometers.

[0038] In this invention, the preferred method for preparing the lobster shell particles is as follows: the lobster shells are washed, crushed, dried, and pulverized before being sieved; the crushed particle size is preferably 8-14 mm, more preferably 10-12 mm; the drying is preferably oven-drying or air-drying; the drying temperature is preferably 60-70℃, more preferably 63-67℃, and the holding time is preferably 12 h; the air-drying time is preferably 24-48 h, more preferably 30-40 h; the target particle size of the pulverized particles is preferably 180-230 μm, more preferably 190-210 μm; the pulverizing equipment is preferably a pulverizer; and the sieve mesh size is preferably 100 mesh.

[0039] In this invention, the volume fraction of HF in the HF-HCl mixed acid solution is preferably 10-10.2%, more preferably 10-10.1%; the volume fraction of HCl in the HF-HCl mixed acid solution is preferably 8.3-8.5%, more preferably 8.4-8.5%; the solute in the HF-HCl mixed acid solution is preferably water; and the water is preferably ultrapure water.

[0040] In this invention, the preferred method for preparing the HF-HCl mixed acid solution is to add HF and HCl to ultrapure water; the preferred volume ratio of HF to HCl in the HF-HCl mixed acid solution is 1:0.83-0.85, more preferably 1:0.84-0.85; the preferred mass concentration of HF is 40-42%, more preferably 40-41%; and the preferred mass concentration of HCl is 36-38%, more preferably 36-37%.

[0041] In this invention, the number of times the mixed pickling is performed is not less than 1 time, preferably not less than 3 times, more preferably not less than 5 times, and even more preferably not less than 10 times.

[0042] In this invention, the time for a single oscillation modification is preferably 1.5 to 2 hours, more preferably 1.7 to 2 hours, and even more preferably 1.9 to 2 hours; the time for a single solid-liquid separation is preferably 12 to 15 minutes, more preferably 13 to 14 minutes.

[0043] In this invention, the equipment for oscillation modification is preferably a shaker; the oscillation modification speed is preferably 160-170 rpm, more preferably 165 rpm. This invention uses a shaker to thoroughly mix lobster shell particles with an HF-HCl mixed acid solution.

[0044] In this invention, the solid-liquid separation is preferably centrifugation; the centrifugation speed is preferably 3800-4000 rpm, more preferably 3900-4000 rpm, and the centrifugation time is preferably 12-15 min, more preferably 13-14 min; after centrifugation, the supernatant is preferably discarded to obtain the acid-washed modified product.

[0045] After obtaining the acid-washed modified material, the present invention washes the acid-washed modified material with water until neutral and then pyrolyzes it to obtain acid-washed modified lobster shell biochar. In this invention, the washing is preferably performed by mixing the acid-modified material with water and then washing; the washing includes sequential shaking and centrifugation; the number of washings is preferably not less than once, more preferably more than five times, and even more preferably more than ten times; the number of washings is preferably until the pH of the supernatant obtained by centrifugation is neutral; the shaking time is preferably 30-45 min, more preferably 35-40 min; the shaking device is preferably a shaker; the centrifugation speed is preferably 3800-4000 rpm, more preferably 3900-4000 rpm, and the time is preferably 12-15 min, more preferably 13-14 min; the supernatant is preferably discarded after centrifugation; the water used for washing is preferably ultrapure water; the solid-liquid ratio of the acid-modified material to water is preferably 1 g:(20-40) mL, more preferably 1 g:(25-35) mL, and even more preferably 1 g:30 mL. This invention, through shaking, ensures that the acid-modified material and water are fully shaken, resulting in a more comprehensive and thorough washing.

[0046] In this invention, the washing process preferably includes drying; the drying is preferably oven drying; the drying equipment is preferably a drying oven; the drying temperature is preferably 60-70°C, more preferably 64-67°C, and the heat preservation time is preferably 12-15 hours, more preferably 13-14 hours.

[0047] In this invention, the pyrolysis is carried out under oxygen-limited conditions; the oxygen-limited conditions are preferably a nitrogen atmosphere; the pyrolysis temperature is preferably 300±2℃ or 600±2℃, more preferably 300±2℃ or 600±2℃, and even more preferably 300℃ or 600℃, and the holding time is preferably 2h; the pyrolysis heating rate is preferably 8~10℃ / min, more preferably 8.5~9.5℃ / min, and even more preferably 9℃ / min; the pyrolysis equipment is preferably a muffle furnace.

[0048] In this invention, the product obtained after pyrolysis is preferably cooled; the final cooling temperature is preferably room temperature; and the cooling is preferably natural cooling.

[0049] This invention also provides the application of the acid-washed modified lobster shell biochar described in the above-described scheme or the acid-washed modified lobster shell biochar prepared by the above-described scheme in the remediation of heavy metal contaminated soil, polycyclic aromatic hydrocarbon contaminated soil and heavy metal-polycyclic aromatic hydrocarbon complex contaminated soil.

[0050] The acid-washed modified lobster shell biochar of the present invention can be used to remediate soil contaminated with heavy metals, soil contaminated with polycyclic aromatic hydrocarbons, and soil contaminated with a combination of heavy metals and polycyclic aromatic hydrocarbons. It is suitable for remediating soil contaminated with toxic heavy metals, and is especially suitable for remediating soil contaminated with lead ions and / or phenanthrene.

[0051] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] (1) The biomass is lobster shells. The lobster shells are washed, crushed, dried and pulverized and then sieved. The sieve mesh size is 100 mesh to obtain lobster shell particles.

[0054] (2) Preparation of HF-HCl mixed acid solution: Add 100-102 mL of HF and 83-85 mL of HCl to the reactor, and add ultrapure water to the reactor to make up to 1 L to obtain HF-HCl mixed acid solution.

[0055] (3) The lobster shell particles and the HF-HCl mixed acid solution are mixed evenly at a solid-liquid ratio of 1:5 to 10 to obtain a premixed solution. The premixed solution is centrifuged once every 1.5 to 2 hours. The centrifugation operation is repeated 5 to 6 times. After removing the supernatant, the acid-washed modified product is obtained.

[0056] (4) Mix the acid-washed modified material with ultrapure water at a solid-liquid ratio of 1:20-40 to obtain a mixture. Centrifuge once every 30-45 minutes. Repeat the centrifugation until the supernatant is neutral. Discard the supernatant and put the obtained acid-washed modified material into an oven to dry, thereby obtaining acid-washed modified biomass.

[0057] (5) The acid-washed modified biomass is pyrolyzed in a muffle furnace at 300°C for 2 hours under oxygen-limited conditions (N2) with a heating rate of 8-10°C / min to obtain acid-washed modified lobster shell biochar.

[0058] The SEM image of the acid-washed modified lobster shell biochar obtained in this embodiment is shown below. Figure 1 As shown.

[0059] Example 2

[0060] The only difference between this embodiment and Embodiment 1 is that the acid-washed modified biomass is pyrolyzed in a muffle furnace at 600°C for 2 hours under oxygen-limited conditions (N2) with a heating rate of 8-10°C / min. The rest of the process is the same as in Embodiment 1.

[0061] The SEM image of the acid-washed modified lobster shell biochar obtained in this embodiment is shown below. Figure 2 As shown.

[0062] Comparative Example 1

[0063] (1) The biomass is lobster shells. The lobster shells are washed, crushed, dried and pulverized and then sieved. The sieve mesh size is 100 mesh to obtain lobster shell particles.

[0064] (2) The lobster shell particles were pyrolyzed in a muffle furnace at 300°C for 2 hours under limited oxygen (N2) conditions with a heating rate of 8-10°C / min to obtain biochar.

[0065] The SEM image of the biochar obtained in this comparative example is shown below. Figure 3 As shown.

[0066] Comparative Example 2

[0067] The only difference between this comparative example and Comparative Example 1 is that the lobster shell particles were pyrolyzed in a muffle furnace at 600°C for 2 hours under oxygen-limited conditions (N2) with a heating rate of 8-10°C / min. The rest of the process was the same as in Comparative Example 1.

[0068] The SEM image of the biochar obtained in this comparative example is shown below. Figure 4 As shown.

[0069] according to Figures 1-4 It can be observed that the surface of lobster shell biochar is rougher after acid washing modification. This is because the acid reacts chemically with the inorganic components, causing the pore walls to collapse, thus making the surface rougher, increasing the specific surface area and total pore volume, thereby providing more adsorption sites and improving the adsorption performance of biochar.

[0070] The acid-washed modified lobster shell biochar prepared in Examples 1-2 of this invention and the biochar prepared in Comparative Examples 1-2 were subjected to BET tests, and the results are shown in Table 1.

[0071] Table 1. BET data for Examples 1-2 and Comparative Examples 1-2

[0072]

[0073] As shown in Table 1, the acid-washed modified lobster shell biochar provided by this invention exhibits a significantly increased specific surface area, as well as improved total pore volume and total micropore volume. This demonstrates that the acid-washing modification of the biochar by this invention produces a substantial structural modification effect.

[0074] Test Example 1

[0075] (1) Biochar adsorption of Pb was performed on the biochar obtained in Comparative Example 1. 2+ experiment;

[0076] (2) In the process of biochar adsorption of Pb 2+ In the experiment: 8 mL of Pb(NO3)2 solution with a concentration of 1–10 mg / L was added, with a solid-liquid ratio of 1:3000; the solution was placed in a shaker and shaken at 170 rpm for 48 hours. The Pb content was then measured. 2+ Concentration, and plot adsorption isotherms.

[0077] Test Example 2

[0078] (1) Biochar adsorption of Pb on the acid-washed modified lobster shell biochar obtained in Example 1 2+ experiment.

[0079] (2) In the process of biochar adsorption of Pb 2+ In the experiment: 8 mL of Pb(NO3)2 solution with a concentration of 1–10 mg / L was added, with a solid-liquid ratio of 1:3000; the solution was placed in a shaker and shaken at 170 rpm for 48 hours. The Pb content was then measured. 2+ Concentration, and plot adsorption isotherms.

[0080] Test Example 3

[0081] (1) Biochar adsorption of Pb on the acid-washed modified lobster shell biochar obtained in Example 2 2+ experiment.

[0082] (2) In the process of biochar adsorption of Pb 2+ In the experiment: 8 mL of Pb(NO3)2 solution with a concentration of 1–10 mg / L was added, with a solid-liquid ratio of 1:6000; the solution was placed in a shaker and shaken at 170 rpm for 48 hours. The Pb content was then measured. 2+ Concentration, and plot adsorption isotherms.

[0083] Test Example 4

[0084] (1) The biochar obtained in Comparative Example 2 was subjected to a biochar adsorption PHE experiment.

[0085] (2) When conducting the biochar adsorption of PHE experiment: add 8 mL of PHE solution with a concentration of 0.2-1 mg / L, and the solid-liquid ratio is 1:8000; place it in a shaker and shake at 170 rpm for 7 days, take it out and measure the PHE concentration, and draw the adsorption isotherm.

[0086] Test Example 5

[0087] (1) The acid-washed modified lobster shell biochar obtained in Example 2 was subjected to a biochar adsorption PHE experiment.

[0088] (2) When conducting the biochar adsorption of PHE experiment: add 8 mL of PHE solution with a concentration of 0.2-1 mg / L, and the solid-liquid ratio is 1:8000; place it in a shaker and shake at 170 rpm for 7 days, take it out and measure the PHE concentration, and draw the adsorption isotherm.

[0089] The adsorption isotherms obtained from test examples 1-3 are as follows: Figure 5 As shown. According to Figure 5 It can be seen that, after acid washing modification, the acid-washed modified lobster shell biochar of the present invention exhibits improved resistance to Pb. 2+ The adsorption effect is significantly improved.

[0090] The adsorption isotherms obtained from test examples 4 and 5 are as follows: Figure 6 As shown. According to Figure 6 It can be seen that, after acid washing modification, the acid-washed modified lobster shell biochar of the present invention has a better adsorption effect on PHE.

[0091] As can be seen from the above embodiments, the acid-washed modified lobster shell biochar provided by the present invention has improved specific surface area, total pore volume, and total micropore volume, and exhibits good adsorption effect on heavy metal ions and non-polar pollutants, especially Pb. 2+ Phosphorus and other compounds exhibit excellent adsorption properties.

[0092] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An acid-washed modified lobster shell biochar with a specific surface area of ​​not less than 33 m². 2 ·g -1 The total pore volume is not less than 0.1 cm³. 3 ·g -1 The total volume of the micropores is not less than 0.014 cm³. 3 ·g -1 ; The particle size of the acid-washed modified lobster shell biochar is 145~165μm; The acid-washed modified lobster shell biochar has pore sizes including micropores, mesopores, and macropores; the micropores have a pore size of 0.5~1.8nm; the mesopores have a pore size of 2~50nm; and the macropores have a pore size of 50~200nm, excluding 50nm. The method for preparing the acid-washed modified lobster shell biochar includes the following steps: (1) Lobster shell particles are mixed with HF-HCl mixed acid solution and acid washed to obtain acid-washed modified material; the mixed acid washing includes sequential shaking modification and solid-liquid separation; the mixed acid washing is performed 5 times; (2) The acid-washed modified material is washed with water until neutral and then pyrolyzed to obtain acid-washed modified lobster shell biochar; the pyrolysis is carried out under oxygen-limited conditions; The volume fraction of HF in the HF-HCl mixed acid solution is 10~10.2%; the volume fraction of HCl in the HF-HCl mixed acid solution is 8.3~8.5%. The duration of a single oscillation modification is 1.5 to 2 hours, and the duration of a single solid-liquid separation is 12 to 15 minutes. The solid-liquid separation is performed by centrifugation; the centrifugation speed is 3800~4000 rpm, and the time is 12~15 min; The pyrolysis temperature was 600±2℃, and the holding time was 2h; The solid-liquid ratio of the lobster shell particles and the HF-HCl mixed acid solution is 1g:(5~10)mL.

2. The method for preparing the acid-washed modified lobster shell biochar according to claim 1, comprising the following steps: (1) Lobster shell particles are mixed with HF-HCl mixed acid solution and acid washed to obtain acid-washed modified material; the mixed acid washing includes sequential shaking modification and solid-liquid separation; the mixed acid washing is performed 5 times; (2) The acid-washed modified material is washed with water until neutral and then pyrolyzed to obtain acid-washed modified lobster shell biochar; the pyrolysis is carried out under oxygen-limited conditions; The volume fraction of HF in the HF-HCl mixed acid solution is 10~10.2%; the volume fraction of HCl in the HF-HCl mixed acid solution is 8.3~8.5%. The duration of a single oscillation modification is 1.5 to 2 hours, and the duration of a single solid-liquid separation is 12 to 15 minutes. The solid-liquid separation is performed by centrifugation; the centrifugation speed is 3800~4000 rpm, and the time is 12~15 min; The pyrolysis temperature was 600±2℃, and the holding time was 2h; The solid-liquid ratio of the lobster shell particles and the HF-HCl mixed acid solution is 1g:(5~10)mL.

3. The preparation method according to claim 2, characterized in that, The lobster shell particles have a particle size of 290~840 micrometers.

4. The preparation method according to claim 2, characterized in that, The heating rate of the pyrolysis is 8~10℃ / min.

5. The application of the acid-washed modified lobster shell biochar according to claim 1 or the acid-washed modified lobster shell biochar prepared by any one of claims 2 to 4 in the remediation of heavy metal contaminated soil, polycyclic aromatic hydrocarbon contaminated soil and heavy metal-polycyclic aromatic hydrocarbon complex contaminated soil.

Images