Modified biochar and porous channel shaped biochar, and preparation method and application thereof

Abstract

The application provides a modified biochar and a porous formed biochar as well as a preparation method and application thereof.The preparation method of the porous formed biochar has the advantages that phenolic resin is insoluble in water but soluble in alcohol solvent, can be compatible with various organic and inorganic fillers, and can provide the required mechanical strength for the formed biochar after crosslinking; compared with other resin systems, the phenolic resin system has the characteristics of low smoke and low toxicity; the selected material is self-produced zinc chloride modified biochar, and the defect of low removal effect of general biochar on atrazine and other organochlorine pesticides is overcome; the modified biochar is formed in the curing process of the adhesive, has a fixed shape, avoids the general biochar particles from entering the environment and causing secondary pollution, and finally obtains the porous high-efficiency formed biochar; the porous formed biochar prepared by the application has the ability of removing atrazine and other organochlorine pesticides, has a regular shape, and has uniform properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biochar material preparation, and particularly relates to modified biochar and porous channel formed biochar, and a preparation method and application thereof. BACKGROUND

[0002] Biochar is a carbon material obtained by pyrolysis of biomass under anaerobic or hypoxic conditions, and is initially applied in soil as a fertilizer to improve soil quality, increase soil fertility, promote crop growth and increase crop yield. Recent studies have shown that biochar can not only be used as an adsorbent to remove various pollutants in the environment, but also has great application potential in carbon sequestration and reduction of greenhouse gas emissions.

[0003] The surface of the original biochar is flat, the pores are loose, and there are almost no micropores, so the removal efficiency of pollutants is low. The powder, small particle size, strong migration and difficult recovery can easily cause secondary pollution. In order to solve the problem of low adsorption performance of the original biochar to pollutants, the types and amounts of oxygen-containing functional groups on the surface of the biochar are increased, and the specific surface area and surface structure characteristics of the biochar are changed. For example, straw is pretreated with zinc chloride and phosphoric acid, and then modified to improve the adsorption. The removal rate of atrazine by the modified biochar is significantly improved. Experimental studies have shown that the pore size of the biochar modified by zinc chloride is small, the arrangement is dense, the microporous structure is obvious, the adsorption sites are increased, and the removal rate of pollutants is increased. In addition, in order to facilitate the transportation of biochar, reduce the problem of small particle size, strong migration and easy loss of particulate biochar, researchers have also carried out research on the forming method of biochar. For example, the existing technology discloses that rice husk charcoal is used as raw material, and hydroxymethyl cellulose is used as adhesive to explore the anti-falling strength and radial maximum compressive stress of the formed charcoal. For example, the existing technology discloses that oil tea shell pyrolysis charcoal powder and adhesive are used as raw materials, and a universal testing machine is used for biomass mixed fuel forming test. By comparing the compressive strength, relaxation density and specific energy consumption of different formed fuels, the influence of the type of adhesive on the fuel quality is determined. However, the conventional adhesive and pressure make the biochar formed into powder after forming, which limits its application in the field of actual environmental remediation.

[0004] Although the existing technology discloses that zinc chloride and the like are used for modification to obtain biochar, the removal rate of organic chlorine pesticides such as atrazine in water by the modified biochar is still not high enough to meet the use requirements. At the same time, the conventional adhesive and pressure make the biochar formed into powder, which enters the environment and causes secondary pollution. Based on the above problems, it is necessary to further improve the existing biochar. SUMMARY

[0005] Therefore, the application provides modified biochar and porous channel formed biochar, and a preparation method and application thereof, so as to solve the defects in the prior art.

[0006] In a first aspect, the application provides a preparation method of modified biochar, comprising the following steps:

[0007] immersing the plant straw in a zinc chloride solution;

[0008] pyrolyzing the soaked plant straw at 400-600 DEG C for 1-3 hours, grinding, and obtaining the modified biochar.

[0009] Preferably, in the preparation method of the modified biochar, the soaking time in the step of immersing the plant straw in the zinc chloride solution is 10-30 hours.

[0010] The mass ratio of the plant straw to the zinc chloride in the zinc chloride solution is (100-120):(45-240).

[0011] Preferably, in the preparation method of the modified biochar, the soaked plant straw is pyrolyzed at 400-600 DEG C for 1-3 hours, ground, and then the ground product is placed in an acid solution, stirred, washed to neutral, and dried, so as to obtain the modified biochar.

[0012] In a second aspect, the application further provides a preparation method of porous channel formed biochar, comprising the following steps:

[0013] dissolving the phenolic resin in an alcohol solvent to obtain an adhesive;

[0014] adding the modified biochar prepared by the preparation method into the adhesive, heating and stirring, and then solidifying to obtain the porous channel formed biochar.

[0015] Preferably, in the preparation method of the porous channel formed biochar, the alcohol solvent in the step of dissolving the phenolic resin in the alcohol solvent comprises at least one of ethanol, methanol and glycerol.

[0016] Preferably, in the preparation method of the porous channel formed biochar, the step of dissolving the phenolic resin in the alcohol solvent to obtain the adhesive is specifically: adding the phenolic resin into the alcohol solvent, stirring at a speed of 1500-2500 r / min for 20-25 min, and obtaining the adhesive.

[0017] Preferably, in the preparation method of the porous channel formed biochar, the mass ratio of the phenolic resin, the alcohol solvent and the modified biochar is (40-50):(100-110):(25-35).

[0018] Preferably, in the preparation method of the porous channel shaped biochar, the modified biochar is added into the adhesive, heated and stirred, and the heating temperature is 85-95 DEG C, and the stirring time is 40-60 min.

[0019] Preferably, in the preparation method of the porous channel shaped biochar, the modified biochar is added into the adhesive, heated and stirred, and then solidified to obtain the porous channel shaped biochar, wherein the solidification temperature is 120-130 DEG C, and the time is 50-60 min.

[0020] In a third aspect, the application further provides the application of the modified biochar prepared by the preparation method or the porous channel shaped biochar prepared by the preparation method as an adsorbent to remove organochlorine pesticides and as a sponge city material.

[0021] The modified biochar and the porous channel shaped biochar and the preparation method thereof have the following beneficial effects compared with the prior art:

[0022] 1. The modified biochar material obtained by using zinc chloride modification overcomes the low removal effect of general biochar on atrazine and other organochlorine pesticides. Experiments show that the removal rate of the modified biochar of the application on atrazine can reach more than 95% after 48 hours of adsorption of different concentrations of atrazine, while the removal rate of the original biochar on atrazine is only 16% when adsorbing an atrazine solution with an initial concentration of 52.475 mg / L. Therefore, the modified biochar of the application has a good removal rate on atrazine. When the mass ratio of zinc chloride to rice straw is 0.85:1, the specific surface area of the prepared modified biochar is the largest, the pore volume is the largest, and the average pore size is the smallest, indicating that the modified biochar prepared by using zinc chloride and rice straw with a mass ratio of 0.85:1 has the best adsorption performance on atrazine.

[0023] 2. The preparation method of the porous channel shaped biochar of the application forms a kind of porous channel high-efficiency shaped carbon-rich material through the coupling technology of modification and shaping, which has a stable shape, a high removal rate on atrazine and other organochlorine pesticides, and can avoid the secondary pollution caused by the entry of biochar particles into the environment. Specifically, the phenolic resin used in the application is not soluble in water and has a small impact on the environment, but is easily soluble in alcohol solvents, can be compatible with various organic and inorganic fillers, and can provide the required mechanical strength and other advantages for the shaped biochar after cross-linking. Compared with other resin systems, the phenolic resin system has the characteristics of low smoke and low toxicity. At the same time, the selected material is the self-produced zinc chloride modified biochar, which overcomes the low removal effect of general biochar on atrazine and other organochlorine pesticides. Further, the modified biochar is shaped during the curing process of the adhesive, has a fixed shape, avoids the entry of general biochar particles into the environment, causes secondary pollution, and finally obtains a porous channel high-efficiency shaped biochar. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0025] Figure 1 SEM electron microscope scanning graph of the modified biochar obtained in Example 2 at 2000 times;

[0026] Figure 2 SEM electron microscope scanning graph of the modified biochar obtained in Example 2 at 15000 times;

[0027] Figure 3 SEM electron microscope scanning graph of the modified biochar obtained in Example 3 at 2000 times;

[0028] Figure 4 SEM electron microscope scanning graph of the modified biochar obtained in Example 3 at 15000 times;

[0029] Figure 5 SEM electron microscope scanning graph of the modified biochar obtained in Example 1 at 2000 times;

[0030] Figure 6 SEM electron microscope scanning graph of the modified biochar obtained in Example 1 at 15000 times;

[0031] Figures 7-9 Macroscopic morphology graph of the porous channel formed biochar prepared in Example 6;

[0032] Figures 10-11 Schematic diagram of hardness test of the porous channel formed biochar in Example 6;

[0033] Figure 12 Graph of the adsorption rate of atrazine reaching stability after repeated leaching 5-6 times of the porous channel formed biochar in Example 6;

[0034] Figure 13 Macroscopic morphology graph of the porous channel formed biochar prepared in Example 7. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0036] It should be noted that the sequence of the following embodiments is not limited as the preferred sequence of the embodiments. In addition, in the description of the present application, the term "comprising" means "including but not limited to". Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values in the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers in the range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in this document, it means that any cited number (fraction or integer) in the indicated range is included.

[0037] The embodiment of the present application provides a preparation method of modified biochar, comprising the following steps:

[0038] S1, soaking plant straw in zinc chloride solution;

[0039] S2, pyrolyzing the soaked plant straw at 400-600 DEG C for 1-3h, grinding, to obtain modified biochar.

[0040] Specifically, the plant straw includes rice straw, wheat straw, corn straw, etc., the plant straw is soaked in the zinc chloride solution, and the plant straw is modified by using zinc chloride as a modifier.

[0041] In some embodiments, in the step of soaking the plant straw in the zinc chloride solution, the soaking time is 10-30h.

[0042] In some embodiments, the mass ratio of the plant straw to zinc chloride in the zinc chloride solution is (100-120):(45-240).

[0043] In some embodiments, the soaked plant straw is pyrolyzed at 400-600 DEG C for 1-3h, ground, the ground product is placed in an acidic solution, stirred, then washed to neutral, dried, and the modified biochar is obtained.

[0044] Specifically, the acid solution used is a 2-5 mol / L nitric acid solution, and the modified biochar is placed in the acid solution and stirred to remove excess zinc chloride on the modified biochar.

[0045] The modified biochar material obtained by modifying the biochar with zinc chloride overcomes the defect that general biochar has a low removal effect on organic chlorine pesticides such as atrazine. Experiments show that the removal rate of atrazine of the modified biochar of the present application can reach more than 95% after 48 hours of adsorption of atrazine with different concentrations, while the removal rate of atrazine of the original biochar is only 16% when adsorbing an atrazine solution with an initial concentration of 52.475 mg / L. Therefore, the modified biochar of the present application has a good removal rate on atrazine.

[0046] Based on the same inventive concept, the present application also provides a preparation method of the porous channel formed biochar, comprising the following steps:

[0047] The phenolic resin is dissolved in the alcohol solvent to obtain the adhesive;

[0048] The modified biochar prepared by the preparation method is added to the adhesive, heated and stirred, and then solidified to obtain the porous channel formed biochar.

[0049] The preparation method of the porous channel formed biochar of the present application forms a porous channel high-efficiency formed carbon material through a modification and forming coupling technology, has a stable shape, has a high removal rate on organic chlorine pesticides such as atrazine, and can avoid the secondary pollution caused by the biochar particles entering the environment. Specifically, the present application utilizes the advantages that the phenolic resin is insoluble in water but soluble in alcohol solvents, is compatible with various organic and inorganic fillers, and can provide the required mechanical strength for the formed biochar after cross-linking, and the phenolic resin system has the characteristics of low smoke and low toxicity compared with other resin systems. The modified biochar material obtained by modifying the biochar with zinc chloride overcomes the defect that general biochar has a low removal effect on organic chlorine pesticides such as atrazine. Further, the modified biochar is formed during the solidification process of the adhesive, has a fixed status, avoids the secondary pollution caused by the general biochar particles entering the environment, and finally obtains the porous channel high-efficiency formed biochar.

[0050] In some embodiments, in the step of dissolving the phenolic resin in the alcohol solvent, the alcohol solvent includes at least one of ethanol, methanol, and glycerol.

[0051] In some embodiments, the step of dissolving the phenolic resin in the alcohol solvent to obtain the adhesive is specifically: the phenolic resin is added to the alcohol solvent, and stirred at a speed of 1500-2500 r / min for 20-25 min to obtain the adhesive.

[0052] In some embodiments, the mass ratio of the phenolic resin, the alcohol solvent and the modified biochar is (40-50):(100-110):(25-35).

[0053] In some embodiments, the modified biochar is added to the adhesive, and the step of heating and stirring is performed at a temperature of 85-95 DEG C for 40-60 min.

[0054] In some embodiments, the modified biochar is added to the adhesive, and the step of heating and stirring is performed at a temperature of 85-95 DEG C for 40-60 min.

[0055] Specifically, in some embodiments, the modified biochar is added to the adhesive, and the mixture is heated in a constant-temperature water bath at 85-95 DEG C for 40-60 min, and the small bubbles generated during production are continuously stirred to escape the container, and then the heated viscous mixture is poured into a mold while hot, and is baked in an oven at 120-130 DEG C for 50-60 min until the phenolic resin is completely cured and formed into a shaped biochar; in the above preparation method, the mixture is continuously stirred because the phenolic resin is subjected to polycondensation reaction during heating, and water and small molecular gases are generated, and the mixture is heated in the water bath at 85-95 DEG C to remove a part of the bubbles and volatilize the ethanol, thereby ensuring the safety of the production process; the mixture is poured into the mold while hot because the mixture is relatively viscous due to the high proportion of biochar, and it is difficult to completely transfer the mixture during pouring, thereby resulting in the loss of biochar.

[0056] Specifically, the shape of the mold used is determined according to the shape of the shaped biochar required, for example, the mold can be in the shape of a cylinder or a cuboid, and correspondingly, the shaped biochar obtained is also in the shape of a cylinder or a cuboid.

[0057] The preparation method of the shaped biochar has the following advantages compared with the prior art:

[0058] 1. The application utilizes the zinc chloride modified biochar regenerated by the pore, and based on the physical forming technology, a pore regeneration-physical forming composite biochar is formed, which is doubly modified and synergistically acts. The composite modified biochar degrades the atrazine organic matter towards high efficiency and cleanness.

[0059] 2. The preparation process of the application is clear, and the production process is repeatable. The phenolic resin as a raw material of the adhesive has good adhesion, and when it is mixed with other substances, it can be bonded with various metal materials or non-metal materials. During use, the performance can be adjusted by adding different curing agents and diluents.

[0060] 3、The porous channel formed biochar prepared by the application is in the form of fine particles, which is easy to lose in the remediation of surface water and groundwater and cannot be recovered and remediated, and the effect is uncontrollable. Compared with Chinese patent application CN114229983A, the application applies biochar to water body treatment; the preparation method of the application combines biochar modification and forming technology, so that the modified biochar has a fixed shape, which can improve the removal efficiency of pollutants by the biochar and further reduce the migration of carbon particles, avoid the entry of biochar powder into the environment medium to cause secondary pollution, and avoid the problems of powder falling and high energy consumption of other modified biochar.

[0061] 4、The porous channel formed biochar prepared by the application has strong ability to remove atrazine and other organochlorine pesticides, and has regular shape and uniform properties.

[0062] Based on the same inventive concept, the application also provides a modified biochar prepared by the above preparation method or an application of the porous channel formed biochar prepared by the above preparation method as an adsorbent to remove organochlorine pesticides and as a sponge city material.

[0063] Specifically, the organochlorine pesticides include but are not limited to atrazine and other organochlorine pesticides. The modified biochar and the porous channel formed biochar of the application can also be used as a sponge city material. At the same time, the modified biochar and the porous channel formed biochar of the application can purify water quality by intercepting atrazine and other organochlorine pesticides, and can be used as a green reaction layer of a sponge city. The modified biochar and the porous channel formed biochar of the application can realize the functions of water storage and water purification, and can help the construction of an ecological city.

[0064] The following further illustrates the modified biochar and the porous channel formed biochar of the application, the preparation method and the application thereof with specific examples. This part further illustrates the content of the application in combination with specific examples, but should not be understood as a limitation of the application. If not specifically stated, the technical means used in the examples are conventional means known to those skilled in the art. Unless specifically stated, the reagents, methods and equipment used in the application are conventional reagents, methods and equipment in the art.

[0065] Example 1

[0066] The application provides a preparation method of a modified biochar, which comprises the following steps:

[0067] S1, rice straw is washed with water, dried and crushed, and reserved;

[0068] S2, 100 parts by weight of rice straw and 85 parts by weight of zinc chloride are added to 925 parts by weight of deionized water, mixed thoroughly, soaked for 24 hours, filtered, and dried in an 80℃ oven, and reserved;

[0069] S3, the soaked rice straw in step S2 is placed in a muffle furnace and pyrolyzed at 500 DEG C for 3h, taken out after pyrolysis is completed and reduced to room temperature, and ground into powder;

[0070] S4, the ground product in step S3 is put into 3mol / L nitric acid, stirred uniformly, placed for 24h, then washed with 80 DEG C hot deionized water until the filtrate is neutral, and finally the modified biochar is dried to obtain modified biochar powder (since the mass ratio of zinc chloride to rice straw is 0.85:1, it is recorded as 0.85:1 modified biochar).

[0071] Example 2

[0072] The embodiment of the present application provides a preparation method of modified biochar, comprising the following steps:

[0073] S1, the rice straw is crushed after water washing and air drying, and reserved;

[0074] S2, 100 parts by weight of rice straw and 0 parts by weight of zinc chloride are added into 500 parts by weight of deionized water, mixed thoroughly, soaked for 24h, filtered, and dried in an 80 DEG C oven, and reserved;

[0075] S3, the soaked rice straw in step S2 is placed in a muffle furnace and pyrolyzed at 500 DEG C for 3h, taken out after pyrolysis is completed and reduced to room temperature, and ground into powder;

[0076] S4, the ground product in step S3 is put into 3mol / L nitric acid, stirred uniformly, placed for 24h, then washed with 80 DEG C hot deionized water until the filtrate is neutral, and finally the modified biochar is dried to obtain modified biochar powder (since the mass ratio of zinc chloride to rice straw is 0:1, it is recorded as 0:1 modified biochar).

[0077] Example 3

[0078] The embodiment of the present application provides a preparation method of modified biochar, comprising the following steps:

[0079] S1, the rice straw is crushed after water washing and air drying, and reserved;

[0080] S2, 100 parts by weight of rice straw and 45 parts by weight of zinc chloride are added into 725 parts by weight of deionized water, mixed thoroughly, soaked for 24h, filtered, and dried in an 80 DEG C oven, and reserved;

[0081] S3, the soaked rice straw in step S2 is placed in a muffle furnace and pyrolyzed at 500 DEG C for 3h, taken out after pyrolysis is completed and reduced to room temperature, and ground into powder;

[0082] S4, the product after grinding in step S3 is put into 3mol / L nitric acid, stirred uniformly, placed for 24h, then washed with 80℃ hot deionized water until the filtrate is neutral, and finally the modified biochar is dried to obtain modified biochar powder (since the mass ratio of zinc chloride to rice straw is 0.45:1, it is recorded as 0.45:1 modified biochar).

[0083] Example 4

[0084] The embodiment of the present application provides a preparation method of modified biochar, comprising the following steps:

[0085] S1, rice straw is crushed after water washing and air drying, and is prepared for use;

[0086] S2, 100 parts by weight of rice straw and 65 parts by weight of zinc chloride are added into 825 parts by weight of deionized water, and after being mixed sufficiently, the rice straw is soaked for 24h, the soaked rice straw is filtered, and is placed in a 80℃ oven for drying, and is prepared for use;

[0087] S3, the soaked rice straw in step S2 is placed in a muffle furnace and pyrolyzed at 500℃ for 3h, and after the pyrolysis is completed and the temperature is reduced to room temperature, the rice straw is taken out and ground into powder;

[0088] S4, the product after grinding in step S3 is put into 3mol / L nitric acid, stirred uniformly, placed for 24h, then washed with 80℃ hot deionized water until the filtrate is neutral, and finally the modified biochar is dried to obtain modified biochar powder (since the mass ratio of zinc chloride to rice straw is 0.65:1, it is recorded as 0.65:1 modified biochar).

[0089] Example 5

[0090] The embodiment of the present application provides a preparation method of modified biochar, comprising the following steps:

[0091] S1, rice straw is crushed after water washing and air drying, and is prepared for use;

[0092] S2, 100 parts by weight of rice straw and 100 parts by weight of zinc chloride are added into 1000 parts by weight of deionized water, and after being mixed sufficiently, the rice straw is soaked for 24h, the soaked rice straw is filtered, and is placed in a 80℃ oven for drying, and is prepared for use;

[0093] S3, the soaked rice straw in step S2 is placed in a muffle furnace and pyrolyzed at 500℃ for 3h, and after the pyrolysis is completed and the temperature is reduced to room temperature, the rice straw is taken out and ground into powder;

[0094] S4, the product after grinding in step S3 is put into 3 mol / L nitric acid, stirred uniformly, placed for 24 h, then washed with 80℃ hot deionized water until the filtrate is neutral, finally the modified biochar is dried to obtain modified biochar powder (since the mass ratio of zinc chloride to rice straw is 1:1, it is called 1:1 modified biochar).

[0095] Example 6

[0096] The embodiment of the present application also provides a preparation method of the porous channel shaped biochar, comprising the following steps:

[0097] S1, the rice straw is crushed after being washed with water and dried, and is ready for use;

[0098] S2, 100 parts by weight of rice straw and 0 parts by weight of zinc chloride are added into 500 parts by weight of deionized water, mixed thoroughly, soaked for 24 h, the soaked rice straw is filtered, and is put into an 80℃ oven for drying, and is ready for use;

[0099] S3, the soaked rice straw in step S2 is placed in a muffle furnace and pyrolyzed at 500℃ for 3 h, taken out after the pyrolysis is completed and reduced to room temperature, and is ground into powder;

[0100] S4, the product after grinding in step S3 is put into 3 mol / L nitric acid, stirred uniformly, placed for 24 h, then washed with 80℃ hot deionized water until the filtrate is neutral, finally the modified biochar is dried to obtain modified biochar powder;

[0101] S5, 50 parts by weight of phenolic resin is dissolved in 100 parts by weight of anhydrous ethanol, stirred at a stirring speed of 2000 rpm at room temperature for 25 min to obtain an adhesive;

[0102] S6, 30 parts by weight of the modified biochar in step S4 is added into the adhesive in step S5, stirred in a magnetic stirrer for 20 min, and gradually forms the phenolic resin dissolved in anhydrous ethanol uniformly wrapped on the surface of the modified biochar;

[0103] S7, the mixture in step S6 is heated in a constant temperature water bath at 90℃ for 50 min, and small gas bubbles generated in the production process are continuously stirred to escape, then the heated viscous mixture is poured into a mold while hot, and is baked in an oven at 125℃ for 60 min, until the phenolic resin is completely cured and shaped, and the porous channel shaped biochar is obtained.

[0104] Example 7

[0105] The embodiment of the present application also provides a preparation method of the porous channel shaped biochar, comprising the following steps:

[0106] S1, rice straw was washed with water, dried in the air, and then crushed for use;

[0107] S2, 100 parts by weight of rice straw and 65 parts by weight of zinc chloride were added to 825 parts by weight of deionized water, mixed thoroughly, and then soaked for 24 h. The soaked rice straw was filtered and dried in an oven at 80°C for use;

[0108] S3, the soaked rice straw in step S2 was placed in a muffle furnace and pyrolyzed at 500°C for 3 h. After the pyrolysis was completed and the temperature was reduced to room temperature, the pyrolyzed rice straw was taken out and ground into powder;

[0109] S4, the ground product in step S3 was placed in 3 mol / L nitric acid, stirred uniformly, and then placed for 24 h. The product was washed with hot deionized water at 80°C until the filtrate was neutral. Finally, the modified biochar was dried to obtain modified biochar powder;

[0110] S5, 50 parts by weight of phenolic resin was dissolved in 100 parts by weight of anhydrous ethanol, and stirred at room temperature at a stirring speed of 2000 rpm for 25 min to obtain an adhesive;

[0111] S6, 30 parts by weight of the modified biochar in step S4 was added to the adhesive in step S5, and stirred in a magnetic stirrer for 20 min to form a uniform coating of phenolic resin on the surface of the modified biochar;

[0112] S7, the mixture in step S6 was heated in a constant temperature water bath at 90°C for 50 min, and the small gas bubbles generated during production were continuously stirred to escape. The heated viscous mixture was then poured into a mold while hot, and baked in an oven at 125°C for 60 min until the phenolic resin was completely cured and formed. Thus, a porous channel formed biochar was obtained.

[0113] Performance characterization

[0114] Figures 1-2 are SEM electron microscope scanning graphs of the modified biochar obtained in Example 2 at 2000 times and 15000 times, respectively (since no zinc chloride modification was used in Example 2, it is actually a raw biochar).

[0115] Figures 3-4 are SEM electron microscope scanning graphs of the modified biochar obtained in Example 3 at 2000 times and 15000 times, respectively.

[0116] Figures 5-6 are SEM electron microscope scanning graphs of the modified biochar obtained in Example 1 at 2000 times and 15000 times, respectively.

[0117] From Figures 1-6As can be seen from the figure, the original biomass charcoal has a relatively rough surface and loose pores, while the modified biomass charcoal has a more clear and obvious pore profile, an increased number of micropores, a developed pore structure and a smaller pore diameter, which is more conducive to adsorption and improves the adsorption performance.

[0118] The modified biomass charcoal obtained in Examples 1-5 was subjected to specific surface area and pore size analysis, and the results are shown in Table 1.

[0119] Table 1 - BET data of the modified biomass charcoal obtained in Examples 1-5

[0120]

[0121] As can be seen from Table 1, after the biomass charcoal powder is modified by zinc chloride activation, it has developed micropores and mesopores, and the number of pores increases, so that the total pore volume and specific surface area increase, and the average pore diameter decreases, thereby improving the adsorption efficiency. When the mass ratio of zinc chloride to rice straw is 0.85:1, the modified biomass charcoal prepared has the largest specific surface area, the largest pore volume and the smallest average pore diameter, indicating that the modified biomass charcoal prepared by using zinc chloride and rice straw in a mass ratio of 0.85:1 has the best adsorption performance for atrazine.

[0122] The modified biomass charcoal obtained in Example 1 was tested for adsorption of atrazine. The specific experimental method is as follows: 0.1 g of the modified biomass charcoal was used to adsorb 40 mL of atrazine solution with different concentrations for 48 h at room temperature of 25°C, and the adsorption of the modified biomass charcoal for atrazine at different concentrations was tested, and the experimental results are shown in Table 2.

[0123] Table 2 - Adsorption results of the modified biomass charcoal for atrazine in Example 1

[0124]

[0125]

[0126] As can be seen from Table 2, 0.1 g of the modified biomass charcoal adsorbed atrazine with different concentrations for 48 h, and the removal rate of atrazine reached more than 95%. However, the modified biomass charcoal obtained in Example 2 had a removal rate of atrazine of only 16% when it was used to adsorb 52.475 mg / L of atrazine solution. It should be noted that since atrazine is difficult to dissolve in water, methanol is added as a cosolvent when preparing the atrazine solution. Specifically, the preparation method of the atrazine solution is as follows: first, dissolve atrazine in methanol, and then add the atrazine dissolved in methanol into water to obtain the atrazine solution. Figures 7-9 Figure 1 is a macroscopic morphology diagram of the porous channel formed biomass charcoal prepared in Example 6 of the present application.

[0127] The hardness of the porous channel formed biochar prepared in Example 6 is tested by using a universal material testing machine Figure 8 , which is a cylindrical body with a thickness of 0.022 m and a diameter of 0.06 m. The formed biochar with a certain thickness (T, m) and diameter (D, m) is placed horizontally on the pressure plate of the testing machine, and the compression rod is vertically downward at a speed to compress the formed biochar until it is crushed, and the maximum pressure value Fmax (N) at the moment when the formed block appears cracks or breaks is recorded max (N), as shown in Figure 10 , 11.

[0128] The hardness formula of the porous channel formed biochar is:

[0129] Through computer monitoring, the maximum pressure value Fmax (N) at the moment when the formed block appears cracks or breaks is read as 57 KN, and the hardness of the formed block is calculated as 43.18 MPa.

[0130] In the column leaching experiment, 2.5 mg / L atrazine leaching solution is carried out in a single column experiment (about 60 g of the porous channel formed biochar obtained in Example 6 is filled in the column) at a flow rate of 1 L / h (10 rpm) in a downward flow manner, and after repeated leaching for 5-6 times, the adsorption rate of atrazine reaches stability Figure 12 ), the adsorption is saturated, and the adsorption capacity is 3.39 mg / kg. The column leaching experiment results are shown in Table 3.

[0131] Table 3 - Atrazine solution column leaching

[0132]

[0133]

[0134] Figure 13 The macroscopic morphology diagram of the porous channel formed biochar prepared in Example 7.

[0135] The porous channel formed biochar prepared in Example 7 Figure 13The results show that the removal rate of atrazine by the porous channel shaped biochar is more than 70% when 0.1 g of the modified biochar is placed in 40 ml of a 2.5 mg / L atrazine solution and shaken for 12 hours. It should be noted that the adsorption rate of atrazine by the modified biochar in Example 1 is more than 95%, and the mass of the modified biochar in the porous channel shaped biochar prepared in Example 7 cannot be determined, so the adsorption data of atrazine by the modified biochar in Example 1 and the porous channel shaped biochar in Example 7 cannot be directly compared. Similarly, the data of the porous channel shaped biochar in Table 3 is obtained through a leaching experiment and is suitable for application in a sponge city, and the adsorption of atrazine by the porous channel shaped biochar in Example 7 is obtained through an adsorption experiment, so the data cannot be directly compared.

[0136] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Application of modified biochar or porous channel shaped biochar as adsorbent for removing organochlorine pesticides. The organochlorine pesticide is atrazine. The preparation method of the modified biochar comprises the following steps: S1, rice straw is washed with water, dried in the air, and then crushed for standby; S2, 100 parts by weight of rice straw and 85 parts by weight of zinc chloride are added to 925 parts by weight of deionized water, mixed thoroughly, soaked for 24 hours, filtered, and then placed in an 80℃ oven for drying, standby; S3, the soaked rice straw in step S2 is placed in a muffle furnace and pyrolyzed at 500℃ for 3 hours, then taken out after cooling to room temperature, and ground into powder; S4, the ground product in step S3 is placed in 3mol / L nitric acid, stirred uniformly, and placed for 24 hours, then washed with 80℃ hot deionized water until the filtrate is neutral, and finally the modified biochar is dried to obtain modified biochar powder; The preparation method of the porous channel shaped biochar comprises the following steps: The phenolic resin is dissolved in the alcohol solvent to obtain an adhesive. The modified biochar prepared by the preparation method is added to the adhesive, heated and stirred, and then solidified to obtain the porous channel shaped biochar. The mass ratio of the phenolic resin, the alcohol solvent and the modified biochar is (40-50):(100-110):(25-35).

2. Use according to claim 1, wherein The phenolic resin is dissolved in the alcohol solvent to obtain an adhesive, specifically: the phenolic resin is added to the alcohol solvent, stirred at a speed of 1500-2500r / min for 20-25min to obtain the adhesive.

3. The use according to claim 1, wherein In the step of adding the modified biochar to the adhesive, heating and stirring, the heating temperature is 85-95℃, and the stirring time is 40-60min.

4. The use according to claim 1, wherein In the step of adding the modified biochar to the adhesive, heating and stirring, and then solidifying to obtain the porous channel shaped biochar, the solidification temperature is 120-130℃, and the time is 50-60min.

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