Micro-mesoporous biomass porous carbon with high specific surface area as well as preparation method and application of micro-mesoporous biomass porous carbon

Abstract

The invention discloses high-specific-surface-area micro-mesoporous biomass porous carbon as well as a preparation method and application thereof. The method comprises the following steps: performing hydrothermal catalytic reaction on tobacco stems in an H2O2 solution to loosen a compact structure and increase oxygen-containing functional groups, fully mixing pretreated tobacco stem hydrothermal carbon and sodium lignin sulfonate in an aqueous solution in a solid-liquid form, adding glutaraldehyde to perform cross-linking reaction, and drying to obtain the tobacco stem hydrothermal carbon / sodium lignin sulfonate composite material. The preparation method comprises the following steps: preparing CaCO3 and tobacco stem into a composite biomass charcoal source with a stable three-dimensional network structure, preparing a composite biomass / CaCO3 precursor through an in-situ coprecipitation method, and finally carrying out high-temperature carbonization to obtain the tobacco stem / lignin composite porous carbon with a micro-mesoporous structure, a high specific surface area and a stable structure. The porous carbon material not only has abundant and mutually communicated hierarchical porous structures and high specific surface area, but also contains abundant active oxygen-containing functional groups, so that the surface characteristics of the porous carbon are improved, more adsorption sites can be provided, and the adsorption performance of the porous carbon material is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of biomass porous carbon, and specifically relates to a high specific surface area micro-mesoporous biomass porous carbon and a preparation method and application thereof. Background Art

[0002] Porous carbon materials have the advantages of rich pore structure, high specific surface area and stable chemical properties. They are one of the most widely used materials for adsorption of organic pollutants. The molecular structure of organic pollutants is complex and changeable, and the molecular size distribution is uneven. Unlike small molecule pollutants, they are difficult to degrade, resulting in serious threats to the ecological environment and human health. The pore structure characteristics of porous carbon play a decisive role in the adsorption performance of antibiotics. Micropores can provide abundant active surfaces, and mesopores can accelerate the mass transfer rate. Therefore, it is very important to prepare micro-mesoporous carbon materials with high specific surface area.

[0003] As the main by-product of the tobacco industry, tobacco stems have a large annual output, most of which are directly landfilled or incinerated in a centralized manner, with low utilization rates, leading to serious resource waste and environmental pollution problems. Tobacco stems are rich in primary pores, heteroatoms (N, O, S, etc.) and metal elements (K, Ca, etc.). They can undergo self-doping and self-activation during the carbonization process, improve the surface properties of porous carbon, and form a developed pore structure. They are high-quality carbon sources for preparing porous carbon. Zhang et al. (IOP Conf. Series: Materials Science and Engineering 2018, 397: 012131) used tobacco stems as raw materials and KOH as an activator to prepare tobacco stem-based modified porous materials for use as adsorbents by combining fermentation, microwave drying, simulation, semi-carbonization and modification. Since it is impossible to evenly compound the activator and biomass through simple physical mixing, the specific surface area and pore volume of the material are only 113.15 m 2 / g and 0.079cm 3 / g, the saturated removal rate of phenol can only reach 73.8%. Chinese patent CN112551524A uses tobacco stems as carbon source, carbonates and oxalates as grinding aids and activators, and prepares tobacco stem-based porous carbon materials through "one-pot ball milling activation". The carbon material has 2100m 2 / g specific surface area and more than 60% mesopore volume. The single mesoporous channel makes the carbon material weak in binding force on pollutants during adsorption and has poor adsorption capacity. Fanny Chipembere et al. (Journal of the Iranian Chemical Society: 2024, 21: 179-191) used phosphoric acid as an activator, compounded tobacco stems with the activator at an impregnation ratio of 1:3, and prepared activated carbon with high iodine value (776.25 mg / g) and high fixed carbon content (85.33%) at 600 ° C. However, due to the fact that the nitrogen, oxygen and other elements rich in tobacco stems are easily decomposed during high-temperature carbonization, the material has fewer nitrogen and oxygen functional groups and poor interface wettability. It can only reach adsorption equilibrium for cypermethrin at 150 minutes. Liu et al. (Journal of Porous Materials 2021, 28: 1629-1642) used a one-step molten salt carbonization method to prepare tobacco stem capacitor carbon, which has a carbonization temperature of 1315 m 2 / g specific surface area and an average pore size of 2nm. The characterization results of the carbon material also show that during the molten salt carbonization process at 850℃, the pre-existing oxygen-containing functional groups in the tobacco stems were destroyed, resulting in a decrease in the density of surface oxygen-containing functional groups, and no nitrogen-containing functional groups were detected.

[0004] However, there are several problems in using agricultural and forestry waste as carbon source to prepare porous carbon for pollutant adsorption: (1) Most current studies use large amounts of highly corrosive activators such as KOH and NaOH to prepare porous carbon with high specific surface area, which leads to severe equipment corrosion and is difficult to industrialize; (2) Crude biomass has poor solubility with activators and templates, resulting in a single pore size distribution of the prepared porous carbon, and an disordered and difficult-to-control pore structure, leading to poor adsorption capacity, slow mass transfer rate, and a narrow range of applications; (3) Most crude biomass can undergo self-doping during the carbonization process, and heteroatoms such as nitrogen and oxygen are easily decomposed during high-temperature carbonization, resulting in poor interface wettability of the prepared carbon material and poor accessibility of adsorption sites.

[0005] Lignin is a natural macromolecule composed of p-hydroxyphenylpropane units, and its reserves in the plant kingdom are second only to cellulose. Lignin has a three-dimensional network structure, high carbon content and abundant oxygen-containing functional groups. It has the advantages of easy modification and structural regulation, and is an ideal carbon source for preparing porous carbon with high specific surface area. Chinese patent CN110482547A uses industrial residue corncob lignin as raw material, and uses phosphoric acid, potassium hydroxide and zinc chloride to activate and prepare lignin-based carbon materials (PACL, PH-CL, ZC-CL). The obtained lignin-based carbon materials have good adsorption effect on Cr(VI) and high removal efficiency, especially PA-CL has better effect, and its adsorption amount of Cr can reach 108.4 mg / g, and the removal rate can reach 54.2%. Li et al. (Research on Chemical Intermediates: 2023, 49: 2209-2232) used three different sources of lignin (corn straw lignin (CSLAC), lignin sulfonate lignin (LSAC) and sugarcane bagasse lignin (BLAC)) as raw materials and prepared different lignin-based biomass activated carbons by KOH activation. The biomass charcoal prepared from corn straw lignin had a carbon content of 1679 m 2 / g specific surface area, and the adsorption capacity of phenol reached 612mg / g. Gao et al. (Chemical Engineering Journal: 2013, 217: 345-353) used lignin from papermaking black liquor as raw material and prepared low-cost, high specific surface area activated carbon by pre-carbonization method-KOH activation. The activated carbon material has a porous structure and an ultra-high specific surface area (2943m 2 / g), and its pore structure is mainly composed of micropores.

[0006] However, there are also some problems in using lignin as a carbon source to prepare porous carbon for pollutant adsorption: (1) The strong etching effect of corrosive activators on the carbon skeleton leads to poor structural stability of lignin carbon, limited increase in specific surface area, and poor adsorption capacity and cyclic stability during antibiotic adsorption. (2) Lignin is prone to shrinkage and aggregation during carbonization, resulting in a disordered pore structure with micropores as the main pore size, which increases the mass transfer resistance during antibiotic adsorption and reduces the adsorption efficiency.

[0007] In order to solve the above problems, researchers have combined different biomasses as carbon sources, combined the advantages of different biomasses, and prepared composite biomass porous carbon with high specific surface area. Yu et al. (Electrochimica Acta. 2019, 327: 134999) proposed a hydrothermal-assisted molecular-scale mixing strategy, combining cellulose-rich sugarcane bagasse and lignin-rich coconut shell, and prepared a composite biomass porous carbon with high specific surface area (3401m 2 / g), well-connected hierarchical porous morphology, good graphitization degree and conductivity of composite biomass porous carbon. An energy density of 118Wh / Kg and excellent cycle performance were achieved in zinc ion capacitors. Akihiro Yamashita (Carbon. 2015, 93: 1080) used the activation effect of crab shells to react with lignin and K 2 CO 3 After mixing, activated carbon was prepared for methane adsorption. The specific surface area of ​​activated carbon prepared from the mixture of lignin and crab shell is 3119m 2 / g, its rich microporous structure makes it have better performance than commercial activated carbon in the process of methane adsorption, but the single microporous structure makes it impossible for this carbon material to take into account both adsorption capacity and adsorption efficiency in terms of pollutant adsorption. Although the above report achieved the purpose of taking advantage of the strengths and weaknesses of the two biomass through the composite, and prepared porous carbon materials with different structural characteristics. However, potassium salts, a highly corrosive activator, is still used, which is highly corrosive to equipment, has high cost and is not conducive to industrial production; in addition, different biomasses are simply physically mixed, with poor compatibility and low composite strength, resulting in uneven pore size distribution of porous carbon materials.

[0008] In summary, although the researchers used the method of combining two biomasses to prepare activated carbon, which greatly optimized its pore structure and adsorption performance, there are still problems such as the strong corrosiveness and large dosage of the activator, which leads to high cost and is not conducive to large-scale production. On the other hand, due to the insolubility of biomass, the composite between biomass and biomass, and between biomass and activator is uneven and poorly dispersed, so that the carbonized pore structure develops unevenly and insufficiently, and a single pore structure cannot guarantee the adsorption capacity and adsorption rate of the porous carbon adsorbent at the same time. Summary of the invention

[0009] In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a method for preparing micro-mesoporous biomass porous carbon with high specific surface area.

[0010] The present invention uses tobacco stems and lignin as carbon precursors, soluble calcium salts and soluble carbonates as calcium sources and precipitants, and glutaraldehyde as a crosslinking agent to prepare high specific surface area composite biomass-based hierarchical porous carbon by in-situ coprecipitation and high temperature carbonization. 2 O 2 The catalyst is used for hydrothermal catalytic reaction to decompose hemicellulose and part of cellulose, so as to loosen the dense structure of tobacco stems and increase their oxygen-containing functional groups. Then, the tobacco stem hydrothermal carbon obtained by pretreatment is fully mixed with sodium lignin sulfonate in aqueous solution in the form of solid and liquid. Then, glutaraldehyde is added to cause cross-linking reaction to form a composite biomass carbon source with a stable three-dimensional network structure. Then, the composite biomass / CaCO is prepared by in-situ coprecipitation method. 3The precursor is carbonized at high temperature to obtain a tobacco stem / lignin composite porous carbon with a micro-mesoporous structure, a high specific surface area and a stable structure.

[0011] Another object of the present invention is to provide a high specific surface area micro-mesoporous biomass porous carbon material prepared by the above method, the porous carbon material not only has a rich, interconnected hierarchical porous structure, a porous structure higher than 2000m 2 / g specific surface area, and contains rich active oxygen-containing functional groups, which improve the surface properties of porous carbon, provide more adsorption sites, and greatly enhance its adsorption performance.

[0012] Another object of the present invention is to provide the use of the above-mentioned high specific surface area micro-mesoporous biomass porous carbon material in the treatment of antibiotic wastewater.

[0013] The purpose of the present invention is achieved through the following technical solutions:

[0014] A method for preparing a high specific surface area micro-mesoporous biomass porous carbon material comprises the following steps:

[0015] (1) Tobacco stem powder and H 2 O 2 After the solutions are mixed, they are placed in a high-pressure reactor and subjected to a hydrothermal catalytic reaction at 150-200°C for 0.5-2h, filtered, and dried to obtain hydrothermal charcoal;

[0016] (2) dissolving the lignin sulfonate in water, mixing the mixture with the tobacco stem hydrochar, and then adding a glutaraldehyde aqueous solution to carry out a cross-linking reaction to obtain a cross-linked product;

[0017] (3) adding a soluble calcium salt solution dropwise to the cross-linked product obtained in step (2) at room temperature, stirring and mixing for 30 minutes to 2 hours after the addition is completed, and then adding a soluble carbonate aqueous solution dropwise, stirring and mixing for 1 to 3 hours after the addition is completed, and drying to obtain a carbon precursor;

[0018] (4) The carbon precursor obtained in step (3) is carbonized in an inert atmosphere, and then acid-washed, water-washed, filtered, and dried to obtain a tobacco stem / lignin composite porous carbon.

[0019] Preferably, in step (1), the tobacco stem powder and H 2 O 2 The mass ratio is 1-2:1-3; more preferably 1-2:1-2.

[0020] Preferably, the particle size of the tobacco stem powder in step (1) is ≤200 mesh; the powder is obtained by crushing the tobacco stem raw material by mechanical crushing and sieving.

[0021] Preferably, in the hydrothermal catalytic reaction system of step (1), H 2 O2 The concentration of the solution is 5 to 15 wt%.

[0022] Preferably, in step (2), the mass ratio of the lignin sulfonate to glutaraldehyde is 3-7:2-10; more preferably 5:2-5; and the mass ratio of the lignin sulfonate to tobacco stem hydrothermal charcoal is 1:2-2:1.

[0023] Preferably, the lignin sulfonate in step (2) is at least one of sodium lignin sulfonate, calcium lignin sulfonate and potassium lignin sulfonate.

[0024] Preferably, the ratio of the lignin sulfonate to water in step (2) is 3.33-6.67 g:100 ml.

[0025] Preferably, the mass concentration of the glutaraldehyde aqueous solution in step (2) is 20 to 200 g / L.

[0026] Preferably, the temperature of the cross-linking reaction in step (2) is 60-100° C. and the time is 2-6 hours.

[0027] Preferably, the mass ratio of the soluble calcium salt, the soluble carbonate in step (3) and the lignin sulfonate in step (2) is 10-18:10-15:3-7; more preferably 10-12:12-15:5.

[0028] Preferably, the soluble calcium salt in step (3) is at least one of calcium chloride, calcium nitrate and calcium acetate; and the soluble carbonate is at least one of potassium carbonate, sodium carbonate and ammonium carbonate.

[0029] Preferably, the mass ratio of calcium carbonate generated by the reaction of the soluble calcium salt and the soluble carbonate in step (3) to the composite biomass is 1:1.

[0030] Preferably, the concentration of the soluble calcium salt solution in step (3) is 111-164 g / L; the concentration of the soluble carbonate aqueous solution is 96-138 g / L.

[0031] Preferably, in step (3), the soluble calcium salt solution and the soluble carbonate aqueous solution are both added dropwise by a peristaltic pump at a stirring flow rate of 0.5 to 5 rpm.

[0032] Preferably, the carbonization in step (4) refers to keeping the temperature at 700-900°C for 0.5-4h; the heating rate of carbonization is 5-10°C / min.

[0033] Preferably, the inert atmosphere in step (4) is at least one of nitrogen, helium and argon.

[0034] Preferably, the acid washing in step (4) refers to washing the carbonized product in a 0.1-1.5 mol / L acid solution for 6-12 h, and the 0.1-1.5 mol / L acid solution is at least one of hydrochloric acid, sulfuric acid and nitric acid.

[0035] Preferably, the water washing in step (4) refers to washing the carbonized product after acid washing with deionized water until the pH is neutral.

[0036] The method mentioned above prepares a micro-mesoporous carbon material with high specific surface area.

[0037] The above-mentioned high specific surface area micro-mesoporous porous carbon material is used for the adsorption and removal of antibiotics.

[0038] Preferably, the antibiotic is at least one of tetracycline hydrochloride, erythromycin, levofloxacin and ciprofloxacin, more preferably tetracycline hydrochloride.

[0039] The preparation method described in the present invention patent will be described in more detail below.

[0040] (1) crushing tobacco stem raw materials by mechanical crushing and screening to obtain tobacco stem powder;

[0041] The purpose of crushing in this step is to better mix the tobacco stem powder with water and catalyst. If the particle size of the tobacco stem powder is too large, it will affect the effect of the hydrothermal process of the tobacco stem powder.

[0042] (2) Take a certain mass of tobacco stem powder and H 2 O 2 The solution is mixed at a solid-liquid ratio of 1:10-20, placed in a high-temperature and high-pressure reactor, and subjected to a hydrothermal catalytic reaction at a temperature of 150-200°C and a heat preservation time of 0.5-2h. After the reaction is completed, the solution is cooled, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0043] The purpose of this step is to promote the decomposition of hemicellulose and cellulose in tobacco stem powder by hydrothermal catalytic reaction at a lower temperature, thereby loosening the dense structure of tobacco stems and removing some soluble impurities contained in tobacco stems. At the same time, rich oxygen-containing functional groups are generated, providing a basis for the subsequent cross-linking reaction and providing Ca for the in-situ coprecipitation process. 2+ Binding site.

[0044] In this step, if the reaction temperature is between 150 and 180°C, the insulation time is controlled between 1 and 2 hours to allow the hemicellulose to be fully pyrolyzed to produce certain pores; if the reaction temperature is between 180 and 200°C, the insulation time is controlled between 0.5 and 1 hour to prevent the hydrothermal time from being too long and the hydrothermal charcoal yield from being too low.

[0045] (3) A certain mass of lignin sulfonate is added into 100 ml of deionized water to be fully dissolved, and the tobacco stem hydrochar obtained in step (2) is added into the lignin sulfonate solution at a mass ratio of 1:2 to 2:1 with the lignin sulfonate. After being fully stirred and mixed, 20 ml of a 100 g / L glutaraldehyde aqueous solution is added, and the mixture is stirred and mixed at 80° C. and reacted for 4 h to obtain a cross-linked product.

[0046] In this step, glutaraldehyde is used as a cross-linking agent for tobacco stems and lignin, which is conducive to obtaining a composite biomass precursor with a stable three-dimensional network structure, in which the oxygen-containing functional groups and pore structure on the surface of tobacco stem hydrothermal carbon provide Ca 2+ The three-dimensional network structure of lignin provides abundant complexing sites for CaCO 3 It has a dispersing effect, and the combination of the two can simultaneously control CaCO 3 Crystal growth and stable dispersion of CaCO 3 Particles, for the realization of CaCO 3 The fully uniform compounding with the composite biomass has a synergistic effect.

[0047] (4) adding the soluble calcium salt solution to the tobacco stem / lignin mixed solution obtained in step (3) at a certain flow rate, stirring and mixing for 30 minutes to 2 hours after the dropwise addition is completed, and then adding the soluble carbonate aqueous solution at a certain flow rate, stirring and mixing for 1 to 3 hours after the dropwise addition is completed, evaporating all the water, and drying the obtained solid to obtain tobacco stem / lignin / nano-CaCO 3 Composite; This step is to make nano-CaCO 3 It can be evenly and stably embedded in the network structure of composite biomass.

[0048] In this step, the order of adding calcium salt and carbonate must be controlled, that is, calcium salt solution is first added to the biomass mixture and then carbonate aqueous solution is added. If carbonate is added first and then calcium salt, carbonate cannot be stably adsorbed and dispersed in the biomass in advance, but is mainly distributed in the aqueous solution, so that the CaCO generated after adding calcium salt is 3 They cannot be combined inside the biomass in an in-situ growth manner, but simply adhere to the surface of the biomass, resulting in weak binding force and uneven distribution between them.

[0049] (5) The tobacco stem / lignin / nano-CaCO obtained in step (4) 3 The composite is carbonized in an inert atmosphere, and then acid-washed, water-washed, filtered and dried to obtain tobacco stem / lignin composite porous carbon.

[0050] In this step, the inert atmosphere can be nitrogen or argon or other inert gases. The carbonization temperature is required to be in the range of 700-900°C and the time is 2-4 hours. If the carbonization temperature is too low or the carbonization time is too short, the nano-CaCO3 The activation effect cannot be exerted, and the formed pores are not rich enough; if the carbonization temperature is too high or the carbonization time is too long, it will lead to excessive carbonization, the porous carbon structure of the composite biomass will collapse, the product yield will be low, the energy consumption will be large, and the production cost will increase.

[0051] The invention provides a micro-mesoporous biomass porous carbon material with high specific surface area prepared by the method.

[0052] The specific surface area of ​​the high specific surface area micro-mesoporous biomass porous carbon prepared by the method of the present invention is in the range of 2000 to 2500 m 2 / g, pore size is 0.5~100nm, total pore volume range is 2.00~2.50cm 3 / g.

[0053] The present invention also provides application of the above-mentioned high specific surface area micro-mesoporous biomass porous carbon material in adsorbing and removing antibiotics.

[0054] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0055] (1) The tobacco stem / lignin composite porous carbon prepared by the method of the present invention has an open and interconnected three-dimensional porous structure, the internal pore structure of which is relatively fully developed, and has a hierarchical pore structure of micropores / mesopores / macropores and a high specific surface area, which provides it with a rapid mass transfer channel and abundant adsorption sites during the adsorption process. It is applied as an adsorbent material for antibiotic-contaminated wastewater, which can achieve efficient and rapid adsorption of antibiotic pollutants, and has good application potential.

[0056] (2) In the preparation process of the tobacco stem / lignin composite porous carbon material of the present invention, the composite lignin and tobacco stems are chemically cross-linked, and the strong carbon framework formed by the tobacco stems during the carbonization process is utilized to stably bind the lignin in the original pores of the tobacco stems, effectively inhibiting the collapse of the lignin during the carbonization process. At the same time, the addition of lignin makes the composite biomass have a three-dimensional network structure, which can fully disperse the calcium carbonate activator, and the pore structure can be fully developed during the carbonization process. By effectively combining the advantages of the two biomasses, the prepared composite porous carbon material has a rich pore structure and oxygen-containing functional groups, and has potential application prospects in antibiotic wastewater treatment adsorption materials. In addition, its raw material reserves are abundant, cheap and easy to obtain, realizing the high added value utilization of tobacco stem waste and industrial lignin resources.

[0057] (3) Low-cost and relatively low-corrosive carbonate and calcium salt are used as mixed activator raw materials, and calcium carbonate activator is prepared by in situ co-precipitation, which improves the compatibility problem between the carbon source and the activator. Calcium carbonate has a "gas phase exfoliation-in situ template" effect during the pyrolysis process. The prepared tobacco stem / lignin porous carbon has a high specific surface area and rich micro-mesoporous structure through a one-step carbonization pyrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a SEM image of the tobacco stem / lignin composite porous carbon prepared in Example 1 of the present invention.

[0059] Figure 2 This is a TEM image of the tobacco stem / lignin composite porous carbon prepared in Example 1 of the present invention.

[0060] Figure 3 It is the nitrogen adsorption-desorption curve and pore size distribution diagram of the tobacco stem / lignin composite porous carbon prepared in Example 1 of the present invention.

[0061] Figure 4 This is a curve showing the relationship between the adsorption capacity and adsorption time of the tobacco stem / lignin composite porous carbon prepared in Example 1 of the present invention for an antibiotic contaminated solution. DETAILED DESCRIPTION

[0062] The present invention is further described in detail below in conjunction with examples and drawings, but the embodiments of the present invention are not limited thereto.

[0063] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. All raw materials, reagents, etc., whose manufacturers are not specified, are conventional products that can be purchased commercially.

[0064] Example 1

[0065] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0066] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0067] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0068] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0069] Example 2

[0070] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the tobacco stem powder was added to 200 ml of 5 wt% H 2 O 2 The solution was stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction was carried out at a temperature of 150°C and a holding time of 2 hours. After the reaction was completed, the reactor was naturally cooled to room temperature, the reaction product was taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0071] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0072] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0073] Tobacco stem / lignin / nano-CaCO 3The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0074] Example 3

[0075] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 15 wt% H 2 O 2 The solution was stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction was carried out at a temperature of 200°C and a holding time of 0.5h. After the reaction was completed, the reactor was naturally cooled to room temperature, the reaction product was taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0076] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0077] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0078] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0079] Example 4

[0080] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0081] Take 5g of calcium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 150g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0082] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 0.5 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 0.5 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0083] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0084] Example 5

[0085] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0086] Take 5g of potassium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 200g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0087] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 5 rpm using a peristaltic pump. After the addition was completed, stirring and mixing continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 5 rpm. After the addition was completed, stirring and mixing continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0088] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0089] Example 6

[0090] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0091] Take 6.67g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 3.33g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0092] 100 mL of calcium nitrate aqueous solution with a mass concentration of 164 g / L was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of sodium carbonate solution with a mass concentration of 106 g / L was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0093] Tobacco stem / lignin / nano-CaCO 3The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0094] Example 7

[0095] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0096] Take 3.33g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 6.67g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0097] 100 mL of calcium acetate aqueous solution with a mass concentration of 158 g / L was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of potassium carbonate solution with a mass concentration of 138 g / L was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0098] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0099] Example 8

[0100] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0101] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0102] 100 mL of 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of 96 g / L ammonium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0103] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 4 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0104] Example 9

[0105] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0106] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0107] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0108] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 700°C at a heating rate of 5°C / min in an argon atmosphere and maintained for 7 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0109] Example 10

[0110] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0111] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0112] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0113] Tobacco stem / lignin / nano-CaCO 3The composite was heated to 900°C at a heating rate of 10°C / min in a nitrogen atmosphere and maintained for 1 hour. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0114] Comparative Example 1 (Compared with Example 1, the tobacco stems were not subjected to hydrothermal catalytic reaction)

[0115] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a mesh size of less than 200. 5 g of sodium lignin sulfonate was added to 100 ml of deionized water to fully dissolve, and then 5 g of tobacco stem powder was added. After stirring evenly, 20 ml of 100 g / L glutaraldehyde aqueous solution was added, and the mixture was reacted in an oil bath at 80° C. for 4 hours to obtain a cross-linked product.

[0116] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0117] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0118] Comparative Example 2 (Compared with Example 1, the two biomasses are not cross-linked)

[0119] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0120] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar and stir evenly.

[0121] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0122] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0123] Comparative Example 3 (Compared with Example 1, without composite lignin)

[0124] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0125] 5 g of tobacco stem hydrothermal charcoal was added into 100 ml of deionized water, and then 20 ml of 100 g / L glutaraldehyde aqueous solution was added, and the mixture was reacted in an 80° C. oil bath for 4 h to obtain a tobacco stem cross-linked product.

[0126] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / nano-CaCO 3 Complex.

[0127] Tobacco stem / nano-CaCO 3The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem porous carbon.

[0128] Comparative Example 4 (Compared with Example 1, without compounding tobacco stems)

[0129] 5 g of sodium lignin sulfonate was added into 100 ml of deionized water to fully dissolve, and then 20 ml of 100 g / L glutaraldehyde aqueous solution was added, and the mixture was reacted in an oil bath at 80° C. for 4 h to obtain a lignin cross-linked product.

[0130] 100 mL of a 111 g / L calcium chloride aqueous solution was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing continued for 2 h. Then, 100 mL of a 138 g / L potassium carbonate solution was added at a speed of 2 rpm. After the addition was completed, stirring and mixing continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain lignin / nano-CaCO 3 Complex.

[0131] Lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain lignin porous carbon.

[0132] Comparative Example 5 (Compared with Example 1, directly using K 2 CO 3 as activator)

[0133] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0134] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0135] 100 mL of potassium carbonate solution with a mass concentration of 138 g / L was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano K 2 CO 3 Complex.

[0136] Tobacco stem / lignin / nano K 2 CO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0137] Comparative Example 6 (Compared with Example 1, directly using CaCO 3 Nanoparticles as activators)

[0138] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0139] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0140] 100 mL of 100 g / L calcium carbonate dispersion was added to the cross-linked product under stirring. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0141] Tobacco stem / lignin / nano-CaCO 3The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0142] Comparative Example 7 (Compared with Example 1, carbonate was added first, and then calcium salt)

[0143] The tobacco stems were mechanically crushed to obtain tobacco stem powder with a size less than 200 mesh. 20 g of the above tobacco stem powder was added to 200 ml of 10 wt% H 2 O 2 The solution is stirred evenly and then transferred into a high-temperature and high-pressure reactor. The hydrothermal catalytic reaction is carried out at a temperature of 180°C and a heat preservation time of 1 hour. After the reaction is completed, the reactor is naturally cooled to room temperature, the reaction product is taken out, filtered, and dried to obtain tobacco stem hydrothermal charcoal.

[0144] Take 5g of sodium lignin sulfonate and add it into 100ml of deionized water to fully dissolve it, then add 5g of tobacco stem hydrochar, stir evenly, add 20ml of 100g / L glutaraldehyde aqueous solution, and react the mixture in an 80℃ oil bath for 4h to obtain a cross-linked product.

[0145] 100 mL of a potassium carbonate solution with a mass concentration of 138 g / L was added to the cross-linked product at a speed of 2 rpm using a peristaltic pump. After the addition was completed, stirring and mixing were continued for 2 h. Then, 100 mL of a calcium chloride aqueous solution with a mass concentration of 111 g / L was added at a speed of 2 rpm. After the addition was completed, stirring and mixing were continued for 3 h. All water was evaporated in an oil bath at 100 ° C. The obtained solid was dried in a blast oven at 120 ° C for 12 h to obtain tobacco stem / lignin / nano-CaCO 3 Complex.

[0146] Tobacco stem / lignin / nano-CaCO 3 The composite was heated to 800°C at a heating rate of 5°C / min in a nitrogen atmosphere and maintained for 2 hours. After it cooled to room temperature, the carbonized product was immersed in a 1 mol / L hydrochloric acid solution for 12 hours, then washed with water until neutral and filtered. The filter cake was moved to a 120°C forced air oven and dried for 1 day to obtain tobacco stem / lignin composite porous carbon.

[0147] Antibiotic adsorption performance test: First, 200 mg / L tetracycline hydrochloride was prepared with deionized water to simulate polluted wastewater, 10 mg of adsorbent was weighed and added to a conical flask containing 50 mL of antibiotic solution, and the conical flask was placed in a constant temperature oscillator at 25°C and oscillated at 150 rpm for 24 hours to achieve adsorption equilibrium. The residual concentration of antibiotics in the solution was measured and the adsorption capacity Q of the adsorbent was calculated by the following formula: e .

[0148] Q e =(C 0 -C e )V / m

[0149] In the above formula, Q e (mg / g) is the equilibrium adsorption capacity of the adsorbent; C 0 (mg / L) is the initial concentration of the antibiotic solution; C e (mg / L) is the concentration of the antibiotic solution when adsorption equilibrium is reached; V (mL) is the volume of the antibiotic solution; m (mg) is the mass of the adsorbent input.

[0150] Table 1 Structural parameters and antibiotic adsorption properties of tobacco stem / lignin composite porous carbon

[0151]

[0152] From Table 1, the specific surface area of ​​the tobacco stem / lignin composite porous carbon prepared in Example 1 is 2437 m 2 / g, the tobacco stem / lignin composite porous carbon prepared in Example 1 has an equilibrium adsorption capacity of 998 mg / g for simulated tetracycline hydrochloride contaminated wastewater with an initial concentration of 200 mg / L, and can reach 95% of the equilibrium adsorption capacity within 20 minutes. It has excellent adsorption performance and adsorption rate, and has obvious application advantages in biomass porous carbon.

[0153] The specific surface area, pore size distribution, adsorption performance and other aspects of the tobacco stem / lignin composite porous carbon prepared in Example 1 and the tobacco stem / lignin composite porous carbon prepared in the comparative example are compared and analyzed. The specific surface area, adsorption capacity and adsorption rate of the tobacco stem / lignin composite porous carbon prepared in Example 1 are significantly improved, and it has a reasonably distributed hierarchical pore structure (38% of mesopores and 52% of micropores), and has excellent adsorption capacity for tetracycline hydrochloride. The reasons why the tobacco stem / lignin composite porous carbon prepared by the present invention has the above excellent performance are analyzed. By chemically cross-linking composite lignin and tobacco stems, the solid carbon framework formed by the tobacco stems during the carbonization process is used to stably bind the lignin in the native pores of the tobacco stems, effectively inhibiting the collapse of lignin during the carbonization process, and at the same time, by adding lignin, the active functional groups of the porous carbon are increased, and its benzene ring structure increases the adsorption sites through Π-Π conjugation; at the same time, the tobacco stem / lignin composite biomass has a three-dimensional network structure and rich Ca 2+ binding site, which facilitates Ca 2+ The uniform dispersion and stability of CaCO in the three-dimensional network are avoided. 3 The rapid nucleation and growth of nano-CaCO uniformly and stably distributed in the three-dimensional network structure of tobacco stem / lignin composite biomass was obtained. 3 Particles, nano-CaCO during high temperature carbonization 3 It can be used as a hard template to fabricate mesopores and some macropores, while nano-CaCO 3 The carbon dioxide released by pyrolysis can be used to vapor-phase stripping or etching of tobacco stem / lignin composite porous carbon to produce micropores, nano-CaCO 3 At the same time, the pore structure of the tobacco stem / lignin composite porous carbon is fully developed as a template and activator to form a tobacco stem / lignin composite porous carbon with interconnected pores and a high specific surface area. Its interconnected micropore / mesopore / macroporous multi-level pore structure and high specific surface area promote the rapid mass transfer and efficient adsorption of antibiotic molecules in the porous carbon pore structure.

[0154] However, in Comparative Example 1, the tobacco stems were not subjected to hydrothermal pretreatment, and the lack of oxygen-containing functional groups to Ca 2+ The complexation of biomass and CaCO 3 It cannot be fully and evenly compounded, the activation effect in the later carbonization process is poor, the pores are not rich enough and there are many closed channels, and the specific surface area is only 1650m 2 / g, the adsorption capacity is 678mg / g; in Comparative Example 2, the tobacco stems and lignin were not cross-linked, the two biomasses were not fully composited, and their respective advantages could not be fully utilized, and the structure of the composite porous carbon obtained was not stable enough; Comparative Examples 3 and 4 both used a single biomass to prepare porous carbon, and the mesoporosity of the tobacco stem porous carbon was relatively high, so the adsorption rate of tetracycline hydrochloride was relatively fast, and 95% of the equilibrium adsorption capacity could be reached within 40min, but the adsorption capacity was not large enough, and the microporosity of the lignin porous carbon was relatively high, and its saturated adsorption capacity for tetracycline hydrochloride was relatively large, reaching 813mg / g, but the adsorption rate was relatively slow; Comparative Example 5 directly used K 2 CO 3 The porous carbon was prepared by impregnation and mixing with composite biomass, K 2 CO 3 By utilizing its gas phase stripping effect and the etching effect of potassium salt, a composite biomass carbon mainly composed of micropores was prepared, which lacked mesopores and macropores, which was not conducive to mass transfer during the adsorption process and affected the adsorption efficiency. 3 The particles are prepared by impregnation and mixing with composite biomass. 3 The biomass can only be combined with the biomass by simple physical attachment, and the binding force is weak, so CaCO cannot be achieved. 3 The pore structure of the composite porous carbon cannot be fully developed during the carbonization process, so its adsorption capacity for antibiotics is limited. Comparative Example 7 uses the sequence of adding carbonate first and then adding calcium salt for coprecipitation reaction. Since carbonate cannot be stably adsorbed and dispersed in biomass in advance, but is mainly distributed in the aqueous solution, the CaCO generated after adding calcium salt is 3 They cannot be combined inside the biomass in an in-situ growth manner, but simply adhere to the surface of the biomass, resulting in weak binding force and uneven distribution between them, and unsatisfactory activation effect.

[0155] Figure 1 This is a scanning electron microscope image of the tobacco stem / lignin composite porous carbon prepared in Example 1 of the present invention. It can be seen from the figure that the prepared composite porous carbon material has a typical honeycomb porous structure and is interconnected.

[0156] Figure 2 This is a transmission electron microscope image of the tobacco stem / lignin composite porous carbon material prepared in Example 1 of the present invention. As can be seen from the image, the composite porous carbon material has a rich pore structure inside, providing a large number of active sites.

[0157] Figure 3This is a nitrogen adsorption-desorption curve and pore size distribution diagram of the tobacco stem / lignin composite porous carbon material prepared in Example 1 of the present invention. It can be seen from the figure that the adsorption-desorption curve of the tobacco stem / lignin composite porous carbon material belongs to type IV. In the area of ​​relatively low relative pressure, the nitrogen adsorption amount increases rapidly, indicating that it has a microporous structure, while the hysteresis loop in the area of ​​relatively high relative pressure indicates that it has a mesoporous structure. The total BET specific surface area of ​​the tobacco stem / lignin composite porous carbon is 2437m 2 / g, and the total pore volume is 2.2cm 3 / g, of which micropores account for 53%, mesopores account for 38%, and macropores account for 9%. The composite porous carbon has a hierarchical pore structure of micropores / mesopores / macroporous pores. The high specific surface area, rich pore structure and reasonable pore size distribution of tobacco stem / lignin composite porous carbon are conducive to achieving rapid mass transfer and high adsorption capacity during the adsorption process.

[0158] Figure 4 This is a curve showing the relationship between the adsorption capacity and adsorption time of the tobacco stem / lignin composite porous carbon prepared in Example 1 of the present invention for the antibiotic contaminated solution. From the figure, it can be seen that the tobacco stem / lignin composite porous carbon prepared in the present invention has excellent adsorption performance for tetracycline hydrochloride, and can reach 95% of the equilibrium adsorption amount within 20 minutes, indicating that the tobacco stem / lignin composite porous carbon has a faster adsorption rate.

[0159] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high specific surface area micro-mesoporous biomass porous carbon material, characterized in that: The following steps are involved: (1) mixing tobacco stem powder with H2O2 solution, subjecting the mixture to a hydrothermal catalytic reaction at 150-200°C for 0.5-2h, filtering, and drying to obtain hydrothermal charcoal; (2) dissolving the lignin sulfonate in water, mixing the mixture with the tobacco stem hydrochar, and then adding a glutaraldehyde aqueous solution to carry out a cross-linking reaction to obtain a cross-linked product; (3) adding a soluble calcium salt solution dropwise to the cross-linked product obtained in step (2) at room temperature, stirring and mixing for 30 minutes to 2 hours after the addition is completed, and then adding a soluble carbonate aqueous solution dropwise, stirring and mixing for 1 to 3 hours after the addition is completed, and drying to obtain a carbon precursor; (4) The carbon precursor obtained in step (3) is carbonized in an inert atmosphere, and then acid-washed, water-washed, filtered, and dried to obtain a tobacco stem / lignin composite porous carbon.

2. The method for preparing a high specific surface area micro-mesoporous biomass porous carbon material according to claim 1, characterized in that: The mass ratio of the lignin sulfonate to glutaraldehyde in step (2) is 3-7:2-10; And / or, the mass ratio of the lignin sulfonate to the tobacco stem hydrothermal charcoal in step (2) is 1:2 to 2:1; And / or, the mass ratio of the soluble calcium salt, the soluble carbonate in step (3) and the lignin sulfonate in step (2) is 10-18:10-15:3-7.

3. The method for preparing a high specific surface area micro-mesoporous biomass porous carbon material according to claim 1 or 2, characterized in that: The mass ratio of the tobacco stem powder to H2O2 in step (1) is 1-2:1-3; and / or, the concentration of the H2O2 solution in step (1) is 5 to 15 wt%; And / or, the particle size of the tobacco stem powder in step (1) is ≤200 mesh.

4. The method for preparing a high specific surface area micro-mesoporous biomass porous carbon material according to claim 1 or 2, characterized in that: The cross-linking reaction temperature in step (2) is 60-100° C. and the time is 2-6 hours; And / or, the mass concentration of the glutaraldehyde aqueous solution in step (2) is 20 to 200 g / L; and / or, the ratio of the lignin sulfonate to water in step (2) is 3.33-6.67 g:100 ml; And / or, the lignin sulfonate in step (2) is at least one of sodium lignin sulfonate, calcium lignin sulfonate and potassium lignin sulfonate.

5. The method for preparing a high specific surface area micro-mesoporous biomass porous carbon material according to claim 1 or 2, characterized in that: The carbonization in step (4) refers to keeping the temperature at 700-900° C. for 0.5-4 h; And / or, the heating rate of the carbonization in step (4) is 5 to 10°C / min.

6. The method for preparing a high specific surface area micro-mesoporous biomass porous carbon material according to claim 1 or 2, characterized in that: The soluble calcium salt in step (3) is at least one of calcium chloride, calcium nitrate and calcium acetate; And / or, the soluble carbonate in step (3) is at least one of potassium carbonate, sodium carbonate and ammonium carbonate.

7. The method for preparing a high specific surface area micro-mesoporous biomass porous carbon material according to claim 6, characterized in that: The concentration of the soluble calcium salt solution in step (3) is 111-164 g / L; and / or, the concentration of the soluble carbonate aqueous solution in step (3) is 96 to 138 g / L; And / or, the soluble calcium salt solution and the soluble carbonate aqueous solution in step (3) are both added dropwise by a peristaltic pump at a stirring flow rate of 0.5 to 5 rpm; And / or, the mass ratio of calcium carbonate generated by the reaction of the soluble calcium salt and the soluble carbonate in step (3) to the composite biomass is 1:

1.

8. The method for preparing a high specific surface area micro-mesoporous biomass porous carbon material according to claim 1 or 2, characterized in that: The acid washing in step (4) refers to washing the carbonized product in a 0.1-1.5 mol / L acid solution for 6-12 hours, wherein the 0.1-1.5 mol / L acid solution is at least one of hydrochloric acid, sulfuric acid and nitric acid.

9. A micro-mesoporous biomass porous carbon material with high specific surface area obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the high specific surface area micro-mesoporous biomass porous carbon material according to claim 9 in the adsorption and removal of antibiotics.

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