A biomass carbon preparation process

Abstract

The invention discloses a biomass carbon preparation process, and relates to the technical field of biomass carbon preparation. The biomass carbon is obtained by carbonizing crop straw and other biomass at low temperature, then carboxylating and then grafting with iron oxide and graphene oxide coated with nano-Al2O3 on the surface. The biomass carbon of the invention can be applied in the field of coal chemical industry, and can replace coal in the preparation of synthesis gas, which has great advantages in reducing carbon dioxide emissions. The biomass carbon of the invention has excellent adsorption and removal performance for organic pollutants, good acid resistance and high temperature resistance, and high environmental protection. Therefore, the biomass carbon of the invention is widely used in the field of coal chemical industry and wastewater treatment, which provides the possibility for the diversified utilization of biomass and is worthy of promotion.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass carbon preparation, and in particular to a biomass carbon preparation process. Background Art

[0002] Biomass carbon refers to a carbon-rich material with a high degree of aromatization and a large specific surface area, produced by anaerobic or anoxic pyrolysis of biomass materials such as sludge, animal manure, and plant residues at a certain temperature. Synthesis gas, primarily composed of carbon monoxide and hydrogen, is a raw gas used as a chemical feedstock. Synthesis gas can be produced from a wide range of sources, including the gasification of solid fuels such as coal or coke, light hydrocarbons such as natural gas and naphtha, and heavy oils through partial oxidation. However, the production of syngas from coal and other raw materials has disadvantages, such as high carbon dioxide emissions, which poses a threat to environmental protection. How to use biomass carbon in syngas production to reduce carbon dioxide emissions and improve environmental performance warrants further study.

[0003] Because biomass carbon contains abundant oxygen-containing functional groups and a large porosity, it has excellent adsorption and stabilization effects on pollutants present in the ecological environment (water, soil, or sediment). Iron oxyhydroxide (FeOOH) is an excellent semiconductor material that can act as a photocatalyst to oxidize and degrade organic matter in wastewater to produce harmless substances such as H2O and CO2 under the action of sunlight. However, iron oxyhydroxide easily decomposes under high temperature and strong acid conditions, resulting in insufficient stability. In addition, the photoquantum efficiency of iron oxyhydroxide is relatively low, resulting in insufficient utilization of light energy and adversely affecting its photocatalytic oxidation degradation rate. Therefore, a biomass carbon material combining iron oxyhydroxide with biomass carbon has been developed. This improves the acid resistance, high temperature resistance, and photocatalytic oxidation degradation reaction rate of the biomass carbon material, thereby improving the adsorption and removal ability of organic matter in wastewater, which is of practical significance. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a biomass carbon preparation process.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The preparation of the biomass carbon comprises the following steps:

[0007] Step S1: washing the straw, drying it, and then crushing it. In a protective gas atmosphere, heating it to 400-500°C, maintaining the constant temperature for 5-6 hours, then taking it out, grinding and sieving it to obtain raw biochar; adding the raw biochar to a nitric acid solution, heating it at 90-100°C for 10-12 hours, cooling it to room temperature, washing it until it is neutral, and vacuum drying it at 80-90°C for 3-4 hours to obtain a carboxylated biochar material;

[0008] Furthermore, the straw is crop straw, the protective gas is nitrogen, the mesh number used for sieving is 100 mesh; the dosage ratio of the original biochar and the nitric acid solution is 1g:40-50mL, and the mass fraction of the nitric acid solution is 68-70%.

[0009] During the reaction process of step S1, the straw is carbonized at high temperature to obtain raw biochar; the raw biochar is acidified with nitric acid solution to obtain carboxylated biochar material;

[0010] Step S2: adding ferric oxyhydroxide to deionized water, ultrasonically dispersing for 30-40 minutes, then adding sodium hexametaphosphate, adjusting the pH to 8-9, heating to 80-90° C. with stirring, adjusting the pH to 10.0-10.8, adding hydrated alumina, continuing stirring for 0.5-1 hour, adjusting the pH to 7.0, continuing stirring for 20-40 minutes, filtering, washing with water, and drying to obtain ferric oxyhydroxide coated with nano-Al2O3;

[0011] Furthermore, the ratio of ferric oxyhydroxide, deionized water, sodium hexametaphosphate, and hydrated aluminum oxide is 5-10 g: 50-60 mL: 3-6 g: 0.05-0.1 g, and the ferric oxyhydroxide is δ-FeOOH (the preparation process of δ-FeOOH refers to 2.1 of the paper "Preparation of δ-FeOOH and FTIR Spectrum of Heat-treated Products");

[0012] During the reaction of step S2, nano-Al2O3 is physically coated on the surface of iron oxyhydroxide by a sol-gel method;

[0013] Step S3: adding ethanol to the iron oxyhydroxide coated with nano-Al2O3 and stirring for 30-40 minutes to obtain an iron oxyhydroxide ethanol solution; then adding oleic acid to ethanol and stirring for 5-10 minutes, and then pouring it into the iron oxyhydroxide ethanol solution, stirring and reacting at 60-70°C for 1-2 hours, drying and grinding to obtain a coated product; adding the coated product to dichloromethane, stirring and adding 3-chloroperoxybenzoic acid, stirring and reacting at room temperature for 4-5 hours to obtain an epoxy product;

[0014] Furthermore, the ratio of the iron oxyhydroxide coated with nano-Al2O3 to ethanol is 1 g: 20-30 mL, the ratio of oleic acid, ethanol, and the iron oxyhydroxide ethanol solution is 5-6 mL: 30-40 mL: 30-40 mL, and the volume fraction of ethanol is 95%; the ratio of the coated product, dichloromethane, and 3-chloroperoxybenzoic acid is 10-12 g: 100-110 mL: 36-40 g;

[0015] During the reaction process of step S3, oleic acid wet-process modifies the surface of the nano-Al2O3-coated ferric oxyhydroxide to generate a coating product containing unsaturated double bonds on the surface; the unsaturated double bonds of the coating product are oxidized by 3-chloroperoxybenzoic acid to generate an epoxy product;

[0016] Step S4: In a protective gas atmosphere, the carboxylated biochar material and toluene are mixed and heated to 40-50°C, pyridine is added, stirred, and the epoxy product is added and stirred for 8-10 hours, and then the temperature is raised to 110-120°C and stirred for 1-2 hours to obtain the hydroxyl product;

[0017] Furthermore, the protective gas is nitrogen, and the ratio of the carboxylated biochar material, toluene, pyridine and epoxy product is 32-35 g: 140-150 mL: 0.5-0.6 mol: 21-23 g;

[0018] During the reaction process of step S4, the carboxyl group of the carboxylated biochar material reacts with the epoxy group of the epoxy product, and the iron oxyhydroxide coated with nano-Al2O3 on the surface is loaded in the biochar to obtain a hydroxyl product;

[0019] Step S5: adding graphene oxide to DMF, adding dichlorothionyl with stirring, and reflux stirring for 24-26 hours to obtain an acyl chloride product; mixing the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide to obtain a mixed solution 1; adding the acyl chloride product to dimethyl sulfoxide to obtain a mixed solution 2, and adding the mixed solution 2 dropwise to the mixed solution 1 in an ice-water bath. After the addition is complete, the mixture is heated to 70-80° C., stirred at a constant temperature for 8-10 hours, and then heated to 100-110° C., continued to stir for 1-2 hours, and distilled under reduced pressure to obtain biomass carbon;

[0020] Furthermore, the usage ratio of graphene oxide, DMF, and thionyl chloride is 5-6 g: 55-65 mL: 15-20 g; the usage ratio of hydroxyl product, pyridine, triethylamine, and dimethyl sulfoxide is 10-12 g: 0.02-0.03 mol: 0.1 mol: 80-90 mL; the usage ratio of acyl chloride product and dimethyl sulfoxide is 8-10 g: 60-70 mL; the usage ratio of mixed solution 1 and mixed solution 2 is 85-95 mL: 65-75 mL;

[0021] During the reaction of step S5, graphene oxide reacts with thionyl chloride to generate an acyl chloride product, which then undergoes an esterification reaction with a hydroxyl product to obtain biomass carbon loaded with graphene oxide and iron oxyhydroxide with the surface coated with nano-Al2O3.

[0022] The present invention provides a process for preparing biochar. The biochar is obtained by carboxylating straw biochar and then grafting it with nano-Al2O3-coated iron oxyhydroxide and graphene oxide. The biochar obtained by the reaction modification of the straw biochar can be mixed with water to form a uniform slurry with a mass fraction of 60-63%. When the slurry is placed in a gasifier, gasification is more complete, allowing it to replace coal in the production of syngas. Furthermore, the production of syngas using biochar reduces carbon dioxide emissions, significantly improving environmental protection.

[0023] Compared with ordinary crop straw biochar, biomass carbon has enhanced adsorption capacity for organic pollutants in water due to the loading of ferric oxyhydroxide and graphene oxide; after ferric oxyhydroxide is coated with nano-Al2O3, the acid resistance and high temperature resistance of ferric oxyhydroxide are improved because nano-alumina has strong acid resistance and excellent thermal stability. At the same time, the ferric oxyhydroxide with the surface coated with nano-Al2O3 is not easy to agglomerate and is evenly dispersed. Ferric oxyhydroxide can absorb sunlight and photocatalytically oxidize and degrade the adsorbed organic pollutants into non-toxic H2O and CO2. In addition, δ-FeOOH has magnetism, which makes the obtained Biomass carbon can be collected by magnetic adsorption, avoiding the adverse effects of biomass carbon on the environment due to its light weight, small particles and difficulty in separation, thereby improving the environmental friendliness of biomass carbon; graphene oxide has the advantages of photosensitivity, good conductivity, and high carrier mobility. By grafting it with ferric oxyhydroxide semiconductor materials and loading it in biomass carbon, the agglomeration phenomenon of graphene oxide is also improved. At the same time, it can increase the migration rate of electrons in biomass carbon, reduce the recombination time of electron-hole pairs, enhance the photocatalytic efficiency of ferric oxyhydroxide, and make up for the low quantum efficiency of ferric oxyhydroxide, so that organic pollutants can be quickly adsorbed and removed. Therefore, the biomass carbon prepared by the present invention has strong adsorption and removal capabilities for organic pollutants and good high temperature resistance and acid resistance, high environmental friendliness, and is worthy of promotion.

[0024] Therefore, the biochar of the present invention can be applied not only to the field of coal chemical industry, but also to the field of wastewater treatment, which is very beneficial for realizing the diversified utilization of biomass materials. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] Example 1

[0027] A biomass carbon, the preparation of which comprises the following steps:

[0028] Step S1: Wash and dry the rice straw and then crush it. In a nitrogen atmosphere, heat it to 400°C, keep the constant temperature for 5 hours, take it out, and grind it through a 100-mesh sieve to obtain raw biochar; add the raw biochar to a nitric acid solution, heat it at 90°C for 10 hours, cool it to room temperature, wash it until it is neutral, and vacuum dry it at 80°C for 3 hours to obtain a carboxylated biochar material; the usage ratio of the raw biochar and the nitric acid solution is 1g:40mL, and the mass fraction of the nitric acid solution is 68%.

[0029] Step S2: adding ferric oxyhydroxide to deionized water, ultrasonically dispersing the mixture for 30 minutes, then adding sodium hexametaphosphate, adjusting the pH to 8, heating the mixture to 80°C with stirring, adjusting the pH to 10.0, adding hydrated alumina, continuing stirring for 0.5 hours, adjusting the pH to 7.0, continuing stirring for 20 minutes, filtering, washing with water, and drying to obtain ferric oxyhydroxide with a surface coated with nano-Al2O3; the amount ratio of ferric oxyhydroxide, deionized water, sodium hexametaphosphate, and hydrated alumina is 5g:50mL:3g:0.05g, and the ferric oxyhydroxide is δ-FeOOH (the preparation process of δ-FeOOH refers to Item 2.1 of the paper "Preparation of δ-FeOOH and FTIR Spectrum of Heat Treatment Product");

[0030] Step S3: adding ethanol to the iron oxyhydroxide coated with nano-Al2O3 and stirring for 30 minutes to obtain an iron oxyhydroxide ethanol solution; then adding oleic acid to ethanol and stirring for 5 minutes, pouring it into the iron oxyhydroxide ethanol solution, stirring and reacting at 60°C for 1 hour, drying and grinding to obtain a coated product; adding the coated product to dichloromethane, stirring and adding 3-chloroperbenzoic acid, stirring and reacting at room temperature for 4 hours to obtain an epoxy product; the amount ratio of the iron oxyhydroxide coated with nano-Al2O3 and ethanol is 1g:20mL, the amount ratio of oleic acid, ethanol, and the iron oxyhydroxide ethanol solution is 5mL:30mL:30mL, and the volume fraction of ethanol is 95%; the amount ratio of the coated product, dichloromethane, and 3-chloroperbenzoic acid is 10g:100mL:36g;

[0031] Step S4: In a nitrogen atmosphere, the carboxylated biochar material and toluene were mixed and heated to 40°C, pyridine was added, and the mixture was stirred. The epoxy product was added and stirred for 8 hours, and then the mixture was heated to 110°C and stirred for 1 hour to obtain the hydroxyl product. The ratio of the carboxylated biochar material, toluene, pyridine, and epoxy product was 32 g:140 mL:0.5 mol:21 g.

[0032] Step S5: adding graphene oxide to DMF, adding dichlorothionyl with stirring, and reacting under reflux and stirring for 24 hours to obtain an acyl chloride product; mixing the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide to obtain a mixed solution 1; adding the acyl chloride product to dimethyl sulfoxide to obtain a mixed solution 2, adding the mixed solution 2 dropwise to the mixed solution 1 in an ice-water bath, after the addition is complete, heating to 70°C, stirring at a constant temperature for 8 hours, and then heating to 100°C, continuing to stir for 1 hour, and distilling under reduced pressure to obtain biomass carbon; the amount ratio of graphene oxide, DMF, and dichlorothionyl is 5g:55mL:15g; the amount ratio of the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide is 10g:0.02mol:0.1mol:80mL; the amount ratio of the acyl chloride product and dimethyl sulfoxide is 8g:60mL; the amount ratio of the mixed solution 1 to the mixed solution 2 is 85mL:65mL.

[0033] Example 2

[0034] A biomass carbon, the preparation of which comprises the following steps:

[0035] Step S1: The corn stalks are washed, dried, and then crushed. In a nitrogen atmosphere, the corn stalks are heated to 450°C, kept at a constant temperature for 5.5 hours, taken out, and ground through a 100-mesh sieve to obtain raw biochar; the raw biochar is added to a nitric acid solution, heated at 95°C for 11 hours, and then cooled to room temperature, washed until neutral, and vacuum-dried at 85°C for 3.5 hours to obtain a carboxylated biochar material; the ratio of raw biochar to nitric acid solution is 1 g:45 mL, and the mass fraction of the nitric acid solution is 69%.

[0036] Step S2: adding ferric oxyhydroxide to deionized water, ultrasonically dispersing for 35 minutes, then adding sodium hexametaphosphate, adjusting the pH to 8, heating to 85°C with stirring, adjusting the pH to 10.4, adding hydrated alumina, continuing stirring for 0.8 hours, adjusting the pH to 7.0, continuing stirring for 30 minutes, filtering, washing with water, and drying to obtain ferric oxyhydroxide with surface coated with nano-Al2O3; the amount ratio of ferric oxyhydroxide, deionized water, sodium hexametaphosphate, and hydrated alumina is 8g:55mL:4.5g:0.08g, and the ferric oxyhydroxide is δ-FeOOH (the preparation process of δ-FeOOH refers to Item 2.1 of the paper "Preparation of δ-FeOOH and FTIR Spectrum of Heat Treatment Product");

[0037] Step S3: adding ethanol to the iron oxyhydroxide with the surface coated with nano-Al2O3 and stirring for 35 minutes to obtain an iron oxyhydroxide ethanol solution; then adding oleic acid to ethanol and stirring for 8 minutes, pouring it into the iron oxyhydroxide ethanol solution, stirring and reacting at 65°C for 1.5 hours, drying and grinding to obtain a coated product; adding the coated product to dichloromethane, stirring and adding 3-chloroperbenzoic acid, stirring and reacting at room temperature for 4.5 hours to obtain an epoxy product; the amount ratio of the iron oxyhydroxide with the surface coated with nano-Al2O3 and ethanol is 1g:25mL, the amount ratio of oleic acid, ethanol, and the iron oxyhydroxide ethanol solution is 5mL:35mL:35mL, and the volume fraction of ethanol is 95%; the amount ratio of the coated product, dichloromethane, and 3-chloroperbenzoic acid is 11g:105mL:38g;

[0038] Step S4: In a nitrogen atmosphere, the carboxylated biochar material and toluene were mixed and heated to 45°C, pyridine was added, and the mixture was stirred. The epoxy product was added and stirred for 9 hours. The mixture was then heated to 115°C and stirred for 1.5 hours to obtain the hydroxyl product. The ratio of the carboxylated biochar material, toluene, pyridine, and epoxy product was 33 g:145 mL:0.5 mol:22 g.

[0039] Step S5: adding graphene oxide to DMF, adding dichlorothionyl with stirring, and reacting under reflux and stirring for 25 hours to obtain an acyl chloride product; mixing the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide to obtain a mixed solution 1; adding the acyl chloride product to dimethyl sulfoxide to obtain a mixed solution 2, adding the mixed solution 2 dropwise to the mixed solution 1 in an ice-water bath, after the addition is complete, heating to 75°C, stirring at a constant temperature for 9 hours, and then heating to 105°C, continuing to stir for 1.5 hours, and distilling under reduced pressure to obtain biomass carbon; the amount ratio of graphene oxide, DMF, and dichlorothionyl is 5.5g:60mL:18g; the amount ratio of the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide is 11g:0.02mol:0.1mol:85mL; the amount ratio of the acyl chloride product and dimethyl sulfoxide is 9g:65mL; ​​the amount ratio of the mixed solution 1 to the mixed solution 2 is 90mL:70mL.

[0040] Example 3

[0041] A biomass carbon, the preparation of which comprises the following steps:

[0042] Step S1: Wash and dry the Salix psammophila straw, then crush it, heat it to 500°C in a nitrogen atmosphere, keep it at a constant temperature for 6 hours, take it out, and grind it through a 100-mesh sieve to obtain raw biochar; add the raw biochar to a nitric acid solution, heat it at 100°C for 12 hours, cool it to room temperature, wash it until it is neutral, and vacuum dry it at 90°C for 4 hours to obtain a carboxylated biochar material; the usage ratio of the raw biochar and the nitric acid solution is 1g:50mL, and the mass fraction of the nitric acid solution is 70%.

[0043] Step S2: adding ferric oxyhydroxide to deionized water, ultrasonically dispersing the mixture for 40 minutes, then adding sodium hexametaphosphate, adjusting the pH to 9, heating the mixture to 90°C with stirring, adjusting the pH to 10.8, adding hydrated alumina, continuing stirring for 1 hour, adjusting the pH to 7.0, continuing stirring for 40 minutes, filtering, washing with water, and drying to obtain ferric oxyhydroxide with a surface coated with nano-Al2O3; the amount ratio of ferric oxyhydroxide, deionized water, sodium hexametaphosphate, and hydrated alumina is 10 g:60 mL:6 g:0.1 g, and the ferric oxyhydroxide is δ-FeOOH (the preparation process of δ-FeOOH refers to Item 2.1 of the paper "Preparation of δ-FeOOH and FTIR Spectrum of Heat Treatment Product");

[0044] Step S3: adding ethanol to the iron oxyhydroxide coated with nano-Al2O3 and stirring for 40 minutes to obtain an iron oxyhydroxide ethanol solution; then adding oleic acid to ethanol and stirring for 10 minutes, pouring it into the iron oxyhydroxide ethanol solution, stirring and reacting at 70°C for 2 hours, drying and grinding to obtain a coated product; adding the coated product to dichloromethane, stirring and adding 3-chloroperbenzoic acid, stirring and reacting at room temperature for 5 hours to obtain an epoxy product; the amount ratio of the iron oxyhydroxide coated with nano-Al2O3 and ethanol is 1g:30mL, the amount ratio of oleic acid, ethanol, and the iron oxyhydroxide ethanol solution is 6mL:40mL:40mL, and the volume fraction of ethanol is 95%; the amount ratio of the coated product, dichloromethane, and 3-chloroperbenzoic acid is 12g:110mL:40g;

[0045] Step S4: In a nitrogen atmosphere, the carboxylated biochar material and toluene were mixed and heated to 50°C, pyridine was added, and the mixture was stirred. The epoxy product was added and stirred for 10 hours. The mixture was then heated to 120°C and stirred for 2 hours to obtain a hydroxyl product. The ratio of the carboxylated biochar material, toluene, pyridine, and epoxy product was 35 g:150 mL:0.6 mol:23 g.

[0046] Step S5: adding graphene oxide to DMF, adding dichlorothionyl with stirring, and reacting under reflux and stirring for 26 hours to obtain an acyl chloride product; mixing the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide to obtain a mixed solution 1; adding the acyl chloride product to dimethyl sulfoxide to obtain a mixed solution 2, adding the mixed solution 2 dropwise to the mixed solution 1 in an ice-water bath, after the addition is complete, heating to 80°C, stirring at a constant temperature for 10 hours, and then heating to 110°C, continuing to stir for 2 hours, and distilling under reduced pressure to obtain biomass carbon; the amount ratio of graphene oxide, DMF, and dichlorothionyl is 6g:65mL:20g; the amount ratio of the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide is 12g:0.03mol:0.1mol:90mL; the amount ratio of the acyl chloride product and dimethyl sulfoxide is 10g:70mL; the amount ratio of the mixed solution 1 to the mixed solution 2 is 95mL:75mL.

[0047] Comparative Example 1

[0048] Compared with Example 3, this comparative example is the original biochar obtained in step S1 of Example 3, that is, the biomass carbon without the surface-coated nano-Al2O3 iron oxyhydroxide and graphene oxide.

[0049] Comparative Example 2

[0050] Compared with Example 3, the ferric oxyhydroxide coated with nano-Al2O3 in step S3 of Example 3 is replaced with the ferric oxyhydroxide in step S2, that is, the surface of the ferric oxyhydroxide is not coated with nano-alumina, to produce biomass carbon.

[0051] Comparative Example 3

[0052] Compared with Example 3, this comparative example is the hydroxyl product obtained in step S4 of Example 3, that is, biomass carbon without introducing graphene oxide and only loading hydroxyl iron with surface coated with nano-Al2O3.

[0053] The biomass carbon prepared by the present invention is further tested for its effect, and the test results are as follows.

[0054] 60 g of each of coal, biomass carbon obtained in Examples 1-3, and Comparative Example 1 were added with 40 mL of distilled water and stirred to prepare slurries. The slurries were then placed in a pulverized coal gasifier under the following gasification conditions: gasification temperature 1380°C, gasification pressure 6.5 MPa, flux (quartz sand) 12 g, and oxygen concentration 99.6 mol% to prepare syngas. The gasification performance was tested, and the test results are recorded in Table 1:

[0055] Table 1:

[0056]

[0057] The data in Table 1 demonstrates that the biochar obtained in Examples 1-3 of the present invention, when used to produce syngas, exhibits gasification performance comparable to that of coal, potentially replacing coal for syngas production. Comparison of Example 3 with Comparative Example 1 demonstrates that the biochar loaded with surface-coated nano-Al₂O₃ iron oxyhydroxide and graphene oxide can be mixed with water to form a more uniform slurry, facilitating more complete combustion of the biochar in the gasifier and achieving better gasification results.

[0058] Fluoranthene, perchloroethylene, and 4-chlorophenol were selected as samples for testing. Under certain pH and temperature conditions, sample solutions with an initial concentration of 50 mg / L, namely, fluoranthene solution, perchloroethylene solution, and 4-chlorophenol solution, were added to reagent bottles, respectively. The biomass carbon obtained in Examples 1-3 and Comparative Examples 1-3 was then added to the fluoranthene solution, perchloroethylene solution, and 4-chlorophenol solution. After standing for 7 days, the concentrations of the sample solutions, namely, the fluoranthene solution, perchloroethylene solution, and 4-chlorophenol solution, were measured. The degradation rates of fluoranthene, perchloroethylene, and 4-chlorophenol were calculated. The degradation rate (%) = (50-sample solution concentration after 7 days) / 50*100. The results are recorded in Table 2.

[0059] Table 2: Test results

[0060]

[0061] According to the data in Table 2, the biochar prepared by the present invention has excellent adsorption and removal performance for organic pollutants. The iron oxyhydroxide coated with Al2O3 on the surface is less affected by strong acidity and high temperature, so the resulting biochar has good high temperature and acid resistance. Comparison of Example 3 with Comparative Example 1 shows that, using ordinary raw biochar without loading iron oxyhydroxide and graphene oxide coated with nano-Al2O3, although ordinary raw biochar is less affected by strong acidity and high temperature, the degradation rate of organic pollutants is significantly reduced, so the prepared biochar has better adsorption and removal performance for organic pollutants. Comparison of Example 3 with Comparative Example 2 shows that, using biochar loaded with iron oxyhydroxide and graphene oxide not coated with nano-Al2O3, the performance of the iron oxyhydroxide not coated with nano-Al2O3 is less affected under room temperature and neutral conditions, but the acid resistance and high temperature resistance are reduced, resulting in a significant decrease in the adsorption and removal performance of the prepared biochar for organic pollutants under high temperature and strong acid conditions. Comparison of Example 3 with Comparative Example 3 shows that only using biomass carbon loaded with iron oxyhydroxide coated with nano-Al2O3 on the surface without introducing graphene oxide to enhance the photocatalytic performance of iron oxyhydroxide is not conducive to improving the degradation rate of organic pollutants.

[0062] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A biomass carbon preparation process, characterized in that: The steps include: Step S1: Wash the straw, dry it and crush it, heat it to 400-500°C in a protective gas atmosphere, keep it at a constant temperature for 5-6 hours, then take it out, grind and sieve it to obtain raw biochar; add the raw biochar to a nitric acid solution, heat it at 90-100°C for 10-12 hours, cool it to room temperature, wash it to neutrality, and vacuum dry it at 80-90°C for 3-4 hours to obtain a carboxylated biochar material; Step S2: adding oxyhydroxide to deionized water, ultrasonically dispersing for 30-40 minutes, then adding sodium hexametaphosphate, adjusting the pH to 8-9, heating to 80-90° C. with stirring, adjusting the pH to 10.0-10.8, adding hydrated aluminum oxide, continuing stirring for 0.5-1 hour, adjusting the pH to 7.0, continuing stirring for 20-40 minutes, filtering, washing with water, and drying to obtain oxyhydroxide with surface coated with nano-Al2O3; Step S3: adding ethanol to the iron hydroxide with the surface coated with nano-Al2O3 and stirring for 30-40 minutes to obtain an iron hydroxide ethanol solution; then adding oleic acid to ethanol and stirring for 5-10 minutes, and then pouring into the iron hydroxide ethanol solution, stirring and reacting at 60-70°C for 1-2 hours, drying and grinding to obtain a coated product; The coated product was added to dichloromethane, 3-chloroperoxybenzoic acid was added with stirring, and the reaction was stirred at room temperature for 4-5 hours to obtain the epoxy product; Step S4: In a protective gas atmosphere, the carboxylated biochar material and toluene are mixed and heated to 40-50°C, pyridine is added, stirred, the epoxy product is added, stirred and reacted for 8-10 hours, and then the temperature is raised to 110-120°C, stirred for 1-2 hours, to obtain a hydroxyl product; Step S5: adding graphene oxide to DMF, adding thionyl chloride with stirring, and reacting with reflux and stirring for 24-26 hours to obtain an acyl chloride product; The hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide are mixed to obtain a mixed solution 1; the acyl chloride product is added to dimethyl sulfoxide to obtain a mixed solution 2; the mixed solution 2 is added dropwise to the mixed solution 1 in an ice water bath; after the addition is completed, the temperature is raised to 70-80°C, and the reaction is stirred at a constant temperature for 8-10 hours, and then the temperature is raised to 100-110°C, and the stirring is continued for 1-2 hours, and the biomass carbon is obtained by distillation under reduced pressure.

2. A biomass carbon preparation process according to claim 1, characterized in that: In step S1, the straw is crop straw, and the mesh number used for sieving is 100 meshes.

3. A biomass carbon preparation process according to claim 1, characterized in that: In step S1, the dosage ratio of the original biochar and the nitric acid solution is 1 g: 40-50 mL, and the mass fraction of the nitric acid solution is 68-70%.

4. A biomass carbon preparation process according to claim 1, characterized in that: In step S2, the usage ratio of ferric oxyhydroxide, deionized water, sodium hexametaphosphate and hydrated aluminum oxide is 5-10 g: 50-60 mL: 3-6 g: 0.05-0.1 g.

5. A biomass carbon preparation process according to claim 1, characterized in that: In step S3, the usage ratio of ferric hydroxide oxide coated with nano-Al2O3 and ethanol is 1g:20-30mL, the usage ratio of oleic acid, ethanol and ferric hydroxide oxide ethanol solution is 5-6mL:30-40mL:30-40mL, and the volume fraction of ethanol is 95%.

6. A biomass carbon preparation process according to claim 1, characterized in that: In step S3, the usage ratio of the coated product, dichloromethane and 3-chloroperbenzoic acid is 10-12 g: 100-110 mL: 36-40 g.

7. A biomass carbon preparation process according to claim 1, characterized in that: In step S4, the usage ratio of carboxylated biochar material, toluene, pyridine and epoxidation product is 32-35 g: 140-150 mL: 0.5-0.6 mol: 21-23 g.

8. A biomass carbon preparation process according to claim 1, characterized in that: In step S5, the usage ratio of graphene oxide, DMF and thionyl chloride is 5-6 g: 55-65 mL: 15-20 g.

9. A biomass carbon preparation process according to claim 1, characterized in that: In step S5, the usage ratio of the hydroxyl product, pyridine, triethylamine and dimethyl sulfoxide is 10-12 g: 0.02-0.03 mol: 0.1 mol: 80-90 mL; the usage ratio of the acyl chloride product and dimethyl sulfoxide is 8-10 g: 60-70 mL.

10. The biomass carbon preparation process according to claim 1, characterized in that: In step S5, the usage ratio of mixed solution 1 to mixed solution 2 is 85-95 mL:65-75 mL.

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