Preparation method and application of composite activated co-pyrolysis biochar

Abstract

The application discloses a preparation method of a composite activated co-pyrolysis biochar and application thereof, and belongs to the field of adsorbent treatment of heavy metal pollution. The preparation method of the co-pyrolysis biochar comprises the following steps: taking original biomass as raw material, cleaning, drying, crushing, sieving, mixing and impregnating the original biomass after drying with magnesium fluosilicate and diethylamine phosphate solution, and then preparing the co-pyrolysis biochar through limited oxygen slow pyrolysis after suction filtration and drying. The application utilizes the biochar to prepare a cheap, green and efficient heavy metal adsorbent, selects heavy metal lead as a research object, and removes lead in water bodies efficiently and at low cost. The method is simple and easy to implement, low in cost, and suitable for popularization and use.

Description

Technical Field

[0001] The present invention belongs to the field of adsorbent treatment of heavy metal pollution, and particularly relates to a preparation method of composite activated co-pyrolysis biochar and application thereof. Background Art

[0002] With the development of global industrialization, heavy metals and their compounds enter the water environment through industrial activities such as mining, smelting, machinery manufacturing, and papermaking. These heavy metals in the water environment are highly toxic, persistent, and difficult to degrade. They are enriched as the food chain extends, and eventually enter the human body, affecting people's normal metabolic activities and causing serious damage to human health and the ecological environment.

[0003] The methods for removing lead from water bodies are mainly divided into three categories: biological methods, physical methods, and chemical methods. Biological methods include microbial complexation, flocculation, adsorption, and phytoremediation; physical methods include solvent extraction, membrane separation technology, ion exchange, and adsorption; chemical methods include redox methods, chemical co-precipitation, and electrolysis. Although there are many methods, they all have some disadvantages. For example, chemical precipitation requires a large amount of chemical agents, which is expensive and the agents themselves are prone to secondary pollution. Although biological methods are relatively low in cost, the types of microorganisms that can remove heavy metals are relatively scarce and difficult to survive in nature. At the same time, it takes a long time to achieve the expected effect. The adsorption method is better than other methods in terms of operating process and treatment effect, and is also more widely used in practical applications.

[0004] Biochar is a solid product obtained by pyrolyzing biomass under anoxic or anaerobic conditions. It boasts a wide range of sources, large specific surface area, well-developed pores, rich functional groups, and strong stability. As a sustainable and environmentally friendly adsorption material, it has attracted widespread attention in the field of heavy metal pollution control. Biochar's graded porosity and rich functional groups provide numerous adsorption sites for heavy metal adsorption. Studies have shown that the presence of mineral components in biochar significantly promotes the adsorption of heavy metals. The presence of mineral components during pyrolysis alters the biochar's surface functional groups and ion exchange capacity, thereby improving its ion exchange capacity.

[0005] The biochar activation process involves further processing the carbonized material using gases (such as H2O and CO2) or chemicals (such as ZnCl2, KOH, and H3PO4). This process aims to alter the internal structure of the carbon, enhance the biochar's functionality, and expand its surface area to enhance adsorption properties, thus facilitating its efficient utilization. Existing co-pyrolysis technology involves adding one or more substances to the original pyrolysis process to increase its efficiency and optimize the post-pyrolysis product processing. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a preparation method and application of composite activated co-pyrolysis biochar, which has a good adsorption effect on Pb in water and reduces its heavy metal mobility.

[0007] In order to achieve the above invention purpose, the present invention adopts the following technical solutions:

[0008] A method for preparing composite activated co-pyrolysis biochar comprises the following steps:

[0009] (1) Pretreatment of raw biochar:

[0010] Using crayfish shells, fish bones and coconut shells as raw materials, the three raw biomasses are cleaned, dried, crushed and sieved to obtain shrimp shell powder, fish bone powder and coconut shell powder; the shrimp shell powder, fish bone powder and coconut shell powder are evenly mixed to obtain mixed biomass;

[0011] (2) Activation:

[0012] The mixed biomass prepared in step (1) is first mixed and impregnated with magnesium fluorosilicate, the mixed solution is shaken and mixed, suction filtered, dried, ground, and sieved; then mixed and impregnated with diethylamine phosphate activation solution, the mixed solution is shaken and mixed, suction filtered, dried, ground, and sieved to obtain a composite activated mixed biomass;

[0013] (3) Co-pyrolysis:

[0014] The composite activated mixed biomass obtained in step (2) is slowly co-pyrolyzed in the presence of limited oxygen at a certain temperature, and then cooled to room temperature to obtain composite activated co-pyrolyzed biochar.

[0015] Preferably, the mixed biomass comprises 15-30% fish bone powder, 20%-40% shrimp shell powder, and 40%-55% coconut shell powder by mass; further preferably, the mixed biomass comprises 15-30% fish bone powder, 30%-40% shrimp shell powder, and 40%-45% coconut shell powder by mass.

[0016] Preferably, in step (1), the raw biomass is cleaned with deionized water, and then dried in an oven at 100-110° C. for 36-48 hours. After drying, the biomass is crushed in a grinder, passed through a 60-mesh sieve, and placed in a plastic bag and stored in a desiccator for use.

[0017] Preferably, in step (2), magnesium fluorosilicate or diethylammonium phosphate is dissolved in deionized water, magnetically stirred at 25° C. for 3 h, and then ultrasonicated for 2 h to obtain an activation solution; further preferably, the concentration of the magnesium fluorosilicate activation solution is 0.2 mol / L, and the concentration of the diethylammonium phosphate activation solution is 0.5 mol / L.

[0018] Preferably, in the step (2), the original biomass obtained in the step (1) is mixed uniformly with the activation liquid in a solid-liquid ratio of 1:5 to 7, and the suspension is then subjected to magnetic stirring for 10 to 12 hours, ultrasonication for 2 to 4 hours, and constant temperature shaking for 3 to 4 hours, filtered at room temperature, and dried at 80 to 100° C. to obtain a solid product, namely the composite activated biomass, which is ground, sieved through a 60-mesh sieve, and sealed for storage.

[0019] Further preferably, in step (2), the temperature in the constant temperature oscillation box is 25±0.5°C and the rotation speed is 195±5 rpm / min.

[0020] Preferably, in step (3), the oxygen-limited slow co-pyrolysis carrier gas is N2, and its gas flow rate is 80-100 mL / min.

[0021] Preferably, in the step (3), when pre-pyrolysis is carried out, the temperature is raised from room temperature to 130-150°C at a heating rate of 7-10°C / min and maintained for 30-40 minutes, so that the oxygen in the tube furnace is exhausted and the biomass is in a dry state; then heated to 700°C at a rate of 5-7°C / min and carbonized at a constant temperature for 2 hours; after the pyrolysis time is reached, the program automatically stops heating and continues to introduce carrier gas. After the temperature naturally cools to room temperature, the pyrolysis product is taken out, which is the composite activated co-pyrolysis biochar.

[0022] A composite activated co-pyrolysis biochar is prepared by adopting the preparation method of the composite activated co-pyrolysis biochar of the present invention.

[0023] The invention discloses an application of composite activated co-pyrolysis biochar, wherein the composite activated co-pyrolysis biochar is used to remove lead ions in water.

[0024] Compared with the prior art, the present invention has the following significant features and positive effects:

[0025] 1. The present invention uses three kinds of original biomass as raw materials to prepare composite activated co-pyrolysis biochar, which is impregnated with activation liquid and then slowly co-pyrolyzed in an oxygen-limited manner. The co-pyrolysis product obtained has considerable stability, and the adsorption effect on lead ions shows that the adsorption capacity of the activated co-pyrolysis biochar for lead ions is significantly improved.

[0026] 2. The shrimp shells, fish bones, and coconut shells used in the present invention are all wastes from the aquaculture industry or its related industries. Heavy metal adsorbents are obtained by activating and pyrolyzing them, which can be utilized as resources and is beneficial for application in environmental fields such as heavy metal wastewater and soil heavy metal remediation.

[0027] 3. The shrimp shell, fish bone, and coconut shell co-pyrolysis biochar prepared in this invention primarily consists of calcium salts such as hydroxyapatite and calcium carbonate. Both calcium salts are inorganic substances with high adsorption capacities, effectively adsorbing metal ions and other compounds through ion exchange, surface adsorption, and dissolution precipitation. Furthermore, the addition of coconut shells creates a more porous structure in the co-pyrolysis components, increasing the specific surface area and enhancing adsorption performance.

[0028] 4. The biochar prepared by the method of the present invention also has a good adsorption effect on other heavy metal ions similar to lead ions (copper, cadmium). At the same time, the method is simple, easy to operate, low-cost, green and environmentally friendly and suitable for promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the pseudo-first-order kinetic model diagram of Comparative Examples 1 and 2 and Examples 3 and 4 for Pb.

[0030] Figure 2 This is a pseudo-second-order kinetic model diagram of Comparative Examples 1 and 2, and Examples 3 and 4 for Pb.

[0031] Figure 3 FTIR images of Comparative Example 3 and Example 4 before and after Pb adsorption.

[0032] Figure 4 These are the N2 adsorption-desorption curves of Comparative Examples 1 and 2 and Examples 3 and 4.

[0033] Figure 5 It is the pore size distribution curve diagram of comparative examples 1 and 2, and embodiments 3 and 4.

[0034] Figure 6 It is the cumulative pore volume curve of comparative examples 1 and 2, and embodiments 3 and 4.

[0035] Figure 7 This is the SEM image of Comparative Example 3.

[0036] Figure 8 This is the SEM image of Example 4. DETAILED DESCRIPTION

[0037] For a better understanding of the present invention, the essential contents and beneficial effects of the present invention are further described in detail below with reference to the examples. The examples are only used to illustrate the present invention and are not intended to limit the present invention.

[0038] Example 1

[0039] The method for adsorbing lead ions using activated co-pyrolysis biochar has the following specific steps:

[0040] (1) Fresh crayfish shells, fish bones, and coconut shells were cleaned, dried, crushed, and passed through a 60-mesh sieve to obtain crayfish shell powder, fish bone powder, and coconut shell powder.

[0041] (2) 33.276 g of MgSiF6 solid was dissolved in 1000 ml of deionized water, magnetically stirred at 25 °C for 3 h, and then ultrasonicated for 2 h to obtain a 0.2 mol / LMgSiF6 activation solution. Fish bones, shrimp shells, and coconut shell powders were mixed uniformly in a mass ratio of 3:2:5 to obtain a mixed biomass. 20 g of the mixed biomass was weighed and added to the 0.2 mol / L MgSiF6 activation solution at a solid-liquid ratio of 1 g:5 mL and mixed uniformly. The suspension was then magnetically stirred for 10 h, ultrasonicated for 2 h, and kept at a constant temperature of (25 ± 0.5) °C and 195 ± 5 rpm / min for 3 h. It was vacuum filtered at room temperature and dried at 80 °C to obtain the MgSiF6 activated mixed biomass SFC, which was ground, sieved through a 60-mesh sieve, and sealed for storage.

[0042] (3) 84.56 g C4H 12 NO4P solid was dissolved in 1000 ml of deionized water, stirred magnetically at 25 °C for 3 h, and then ultrasonicated for 2 h to obtain 0.5 mol / L C4H 12 NO4P solution. The MgSiF6 activated mixed biomass SFC obtained in step (2) was added to 0.5 mol / L C4H 12 The suspension was mixed evenly with NO4P solution, and then subjected to magnetic stirring for 10 h, ultrasonication for 2 h, and constant temperature shaking at (25±0.5)°C and 195±5 rpm / min for 3 h. It was vacuum filtered at room temperature and dried at 80°C to obtain the composite activated mixed biomass SFC, which was ground, passed through a 60-mesh sieve, and sealed for storage.

[0043] (4) Weigh several 5g portions of the composite activated mixed biomass SFC obtained in step (3) and place them in a rectangular porcelain boat, which is then placed in a tubular electric furnace; introduce N2, heat the mixture to 130°C, maintain for 30 min, then heat the mixture to 700°C, and carbonize at a constant temperature for 2 h; after the pyrolysis time is reached, the program automatically stops heating and continues to introduce N2. After the temperature naturally cools to room temperature, the pyrolysis product is taken out, which is the composite activated co-pyrolysis biochar SFCC700. After weighing, grind it through a 60-mesh sieve, and seal it for storage.

[0044] (5) The composite activated co-pyrolysis biochar SFCC700 obtained in step (4) was subjected to an adsorption kinetics experiment. 0.05 g of SFC700 was placed in a 100 mL conical flask and a mass concentration of 500 mg·L was prepared with Pb(NO3)2. -1 Pb 2+Solution 50mL, deionized water as background solution, 0.1mol·L -1 The pH of the solution was adjusted to (5.0±0.05) with HNO3 or NaOH. The adsorption system was placed at (25±0.5)℃ and shaken in the dark at 195±5rpm / min after covering. Samples were taken at 0, 5, 20, 40, 60, 90, 150, 240, 480, 720min and 1440min, respectively, and transferred to a 50mL centrifuge tube and centrifuged at 4500r·min. -1 Centrifuge for 10 minutes, take the supernatant and filter it through a 0.45 μm water filter membrane, dilute it with 1% HNO3 and determine the Pb content in the solution using a novAA300 flame atomic absorption spectrometer. 2+ concentration.

[0045] In the adsorption kinetics experiment, the experimental conditions were that the solid-liquid ratio of biochar to lead ion solution was 1:1000, and Pb 2+ The concentration is 500 mg / L, and the pH in the system is preferably (5.0±0.05).

[0046] Example 2

[0047] This embodiment is basically the same as embodiment 1, except that: in this embodiment, the mass ratio of fish bones, shrimp shells and coconut shell powders is adjusted to 3:6:11 and mixed evenly, and subsequent adsorption experiments are carried out.

[0048] Example 3

[0049] This embodiment is basically the same as embodiment 1, except that: in this embodiment, the mass ratio of fish bones, shrimp shells and coconut shell powders is adjusted to 3:8:9 and mixed evenly, and subsequent adsorption experiments are carried out.

[0050] Example 4

[0051] This embodiment is basically the same as embodiment 1, except that: in this embodiment, the mass ratio of fish bones, shrimp shells and coconut shell powders is adjusted to 3:3:4 and mixed evenly, and subsequent adsorption experiments are carried out.

[0052] Comparative Example 1

[0053] This comparative example is basically the same as Example 4, except that in this example, the biomass was only subjected to C4H 12 NO4P was activated with activation solution and then co-pyrolyzed.

[0054] Comparative Example 2

[0055] This embodiment is basically the same as embodiment 4, except that the biomass in this embodiment is only activated with MgSiF6 solution and then subjected to co-pyrolysis.

[0056] Comparative Example 3

[0057] This comparative example is basically the same as Example 4, except that the biomass in this example is directly co-pyrolyzed without activation treatment.

[0058] Comparative Example 4

[0059] This comparative example is basically the same as Example 1, except that the biomass in this example is only shrimp shell powder.

[0060] Comparative Example 5

[0061] This comparative example is basically the same as Example 1, except that the biomass in this example is only fish bone powder.

[0062] Comparative Example 6

[0063] This comparative example is basically the same as Example 1, except that the biomass in this example is only coconut shell powder.

[0064] Analysis of adsorption kinetics model of biochar

[0065] The adsorption kinetic model parameters of the above embodiments and comparative examples are shown in Table 1, and the model fitting curves are shown in Table 1. Figures 1 and 2 From the fitting results, we can see that in Pb 2+ The initial concentration was 500 mg·L -1 Under these conditions, the kinetic trend of the adsorption system consists of three stages: rapid adsorption, slow adsorption and adsorption equilibrium. 2+ The adsorption amount of Pb increased rapidly within the first hour, then gradually slowed down and reached adsorption equilibrium in 24 hours. In the initial stage, due to the large number of vacancies in the active sites on the outer surface of biochar, Pb 2+ The adsorption rate slowed down after 1 hour because the Pb adsorbed on the outer surface of biochar 2+ The activated carbon begins to migrate and bind to the active sites on the pores of the biochar. Compared with the unactivated biochar, the time required for the overall equilibrium in the adsorption system of the activated embodiment is shorter and the adsorption rate is faster.

[0066] It can be seen from the figure that the pseudo-first-order kinetic equation can fit the initial stage of adsorption well (t<60min), and gradually deviate from the adsorption process after t>60min. And it can be seen from Table 1 that the model fitting can determine the R 2 (0.911<R 2 <0.982) The quasi-second-order model can determine R 2 Low (R 2 =0.999), the entire adsorption process cannot be well evaluated. Therefore, liquid film diffusion is not the main cause of Pb 2+ The only factor that affects the adsorption rate during the adsorption process.

[0067] Compared with the pseudo-first-order kinetic model, the pseudo-second-order kinetic equation fitting coefficient of determination R 2 are all 0.999, which is closer to 1, and the linear correlation is significant, which can more accurately fit the entire adsorption process, which means that chemical adsorption is involved in the adsorption process. 2+ The adsorption mechanism on co-pyrolysis biochar involves physical adsorption and chemical adsorption, among which chemical adsorption dominates the reaction process.

[0068] As can be seen from Table 1, the adsorption capacity of the co-pyrolysis biochar obtained by co-pyrolysis of biomass after activation was greatly improved compared with that before activation. The increase in the adsorption rate constant k value means that the reaction rate in each system has been accelerated to varying degrees, which is conducive to accelerating the formation of the equilibrium system.

[0069] Table 1 Parameters of biochar adsorption kinetic model

[0070]

[0071] a Actual adsorption capacity of biochar

[0072] The number and type of oxygen-containing functional groups on the surface are one of the important mechanisms for biochar to adsorb heavy metals. The isolated electron pairs on the oxygen atoms in the negatively charged oxygen-containing functional groups (such as -COOH, -OH and C=O, etc.) form coordination bonds with the outer orbitals of heavy metal ions, which can react with heavy metal cations to fix heavy metal ions. At the same time, biochar also has highly stable aromatic ring structures that can also bind to heavy metals. Figure 3 Pb adsorption by co-pyrolysis biochar before and after composite activation 2+ The FTIR spectra before and after were analyzed.

[0073] The results are as follows Figure 3 As shown, the unactivated SFCC700 of Comparative Example 3 is located at 3500 cm -1 The peak near the adsorption of Pb 2+ After that, it decreased significantly, indicating that the alcoholic hydroxyl group and the phenolic hydroxyl group participated in the reaction of Pb 2+ adsorption and complexation occurred with it; 1680~1620cm -1 The peak intensity of carbonyl C=O functional group at the 2+ The complexation effect also contributes greatly; after composite activation of Example 4, SFCC700 is located at 1460, 1410, 1050, 960, 610cm -1 and 565cm -1 Nearby CO3 2- With PO4 3-The reduction degree of stretching vibration peak is greater than that of unactivated SFCC700 in comparative example 3, indicating that the carbonate and phosphate in SFCC700 after composite activation have an effect on Pb 2+ The precipitation effect is greater than that of unactivated SFCC700; and at 2920cm -1 and 2850cm -1 The stretching vibration peaks of aliphatic hydrocarbons and cycloalkanes -CH3 and -CH2 also decreased after adsorption, indicating that they also participated in the entire adsorption process.

[0074] Table 2 BET surface area, average pore size and pore volume parameters of co-pyrolysis biochar

[0075]

[0076] As can be seen from Table 2, the BET specific surface area of ​​Examples 3 and 4 obtained by the two-step composite activation treatment is significantly larger than that of Comparative Examples 1 and 2 obtained by the one-step activation treatment. On the one hand, the addition of high specific surface area coconut shell in the co-pyrolysis biochar component increases the specific surface area of ​​the co-pyrolysis product, increases the functional groups that can be carried, and has a stronger electrostatic adsorption capacity for substances. On the other hand, after the two-step composite activation, the internal pores of the co-pyrolysis biochar are completely opened. At the same time, the removal of aliphatic and volatile compounds and the appearance of vascular bundle structure during the pyrolysis process greatly increase the specific surface area.

[0077] Depend on Figure 4 The adsorption-desorption isotherms of nitrogen (N2) for the co-pyrolyzed biochars treated with different treatments show consistent trends across treatment groups, demonstrating a Type IV isotherm, characteristic of mesoporous adsorbents. At relatively low relative pressures, this is characterized by monolayer adsorption. When the relative pressure is greater than 0.4, multilayer adsorption persists. At higher relative pressures, the adsorbed gas in the biochar pores gradually transforms into a liquid state, causing capillary condensation. Subsequently, adsorption occurs only on the outer surface, which is much smaller than the surface area, resulting in a flat curve. When the relative pressure approaches 1, the curve exhibits a rapid upward trend, indicating that the co-pyrolyzed biochar has a large pore size distribution and is predominantly mesoporous. This also suggests that the biochar is a mesoporous adsorbent, demonstrating that adsorption of heavy metals and organics exhibits a relatively short monolayer adsorption followed by a gradual transition to multilayer adsorption.

[0078] The adsorption performance of heavy metal ions is affected by the specific surface area, pore volume, and pore structure of the biochar. The figure clearly shows that the biochar mesopores are mostly distributed between 2nm and 20nm. The pore size distribution shows that the pores of the co-pyrolysis biochar are mainly mesopores, while the proportion of macropores gradually decreases. The pore volume is mainly contributed by mesopores with pore sizes of 2nm to 20nm. The figure shows that the pore volume of the co-pyrolysis biochar after two-step composite activation is significantly increased compared to the co-pyrolysis biochar after one-step activation. This may be because the dual activation effect makes the decomposition of organic matter more complete, and the volatile compounds are fully volatilized and dissipated. After the two-step activation, the original macropores are collapsed by N2 shock to form more mesopores, resulting in a rapid increase in pore volume.

[0079] Depend on Figure 7-8 It can be seen that the structure of the biochar after composite activation has a higher porosity and total pore volume. After activation treatment, most organic compounds are fully volatilized and decomposed under 700°C pyrolysis, and more carbon-containing substances are converted into gas products, making it easier to form pores. Compared with Comparative Example 3, the pores of Example 4 are larger after composite activation and the thickness of the pore wall is reduced. This is attributed to the volatilization of organic matter during the progressive heat treatment process, which helps to form deep channels with clear pores. As the pyrolysis proceeds, these channels become more obvious. After composite activation treatment, SFCC700 gradually forms some mesopores at a pyrolysis temperature of 700°C. In addition, the macropores collapse to a certain extent, forming more mesopores, and the external collapsed part falls on the surface of the macropores. With the continuous introduction of N2 atmosphere during the pyrolysis process, the multilayer aromatic structure in the biochar dominates, which may be the main reason for the formation of the honeycomb structure.

[0080] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications should fall within the scope of the invention as claimed.

Claims

1. A method for preparing composite activated co-pyrolysis biochar, characterized in that: The following steps are involved: (1) Pretreatment of raw biomass: washing, drying, crushing, and sieving the raw biomass shrimp shells, fish bones, and coconut shells to obtain shrimp shell powder, fish bone powder, and coconut shell powder; uniformly mixing the shrimp shell powder, fish bone powder, and coconut shell powder to obtain mixed biomass; the mixed biomass is composed of 15-30% fish bone powder, 30-40% shrimp shell powder, and 40-45% coconut shell powder by mass percentage; (2) Activation: The mixed biomass of step (1) is mixed and impregnated with the magnesium fluorosilicate activation solution, filtered, dried, ground, and sieved; Then, the activated biomass is mixed and impregnated with a diethylamine phosphate activation solution, filtered, dried, ground, and sieved to obtain a composite activated mixed biomass; (3) Co-pyrolysis: The composite activated mixed biomass obtained in step (2) is subjected to oxygen-limited slow co-pyrolysis to obtain composite activated co-pyrolysis biochar.

2. The method for preparing composite activated co-pyrolysis biochar according to claim 1, characterized in that: The concentration of the magnesium fluorosilicate activation solution is 0.2 mol / L, and the concentration of the diethylamine phosphate activation solution is 0.5 mol / L.

3. The method for preparing composite activated co-pyrolysis biochar according to claim 1, characterized in that: The solid-liquid ratio of the mixed impregnation in step (2) is 1 g:5-7 mL.

4. The method for preparing composite activated co-pyrolysis biochar according to claim 1, characterized in that: In step (3), the oxygen-limited slow co-pyrolysis is to heat the temperature to 130-150°C at a heating rate of 7-10°C / min in an inert atmosphere, stay for 30-40 minutes, and perform pre-pyrolysis; then heat the temperature to 700°C at a heating rate of 5-7°C / min, and carbonize at a constant temperature for 2 hours; after the pyrolysis time is reached, the program automatically stops heating and continues to introduce carrier gas. After the temperature naturally cools to room temperature, the pyrolysis product is taken out, which is the composite activated co-pyrolysis biochar.

5. The method for preparing composite activated co-pyrolysis biochar according to claim 1, characterized in that: In step (1), the raw biomass is placed in an oven at 100-110° C. and dried for 36-48 hours; after drying, the raw biomass is placed in a grinder and pulverized, and passed through a 60-mesh sieve.

6. A composite activated co-pyrolysis biochar, characterized by: The biochar is prepared by the method for preparing the composite activated co-pyrolysis biochar according to any one of claims 1 to 5.

7. An application of composite activated co-pyrolysis biochar, characterized by: The composite activated co-pyrolysis biochar according to claim 6 is used to remove lead ions in water.

Images