Method for preparing activated carbon by using black liquor self-activation combined with microemulsion solid template method and application thereof

Abstract

The invention relates to the technical field of environmental protection and waste resource recycling, in particular to a method for preparing activated carbon through black liquor self-activation combined with a microemulsion solid template method and application of the activated carbon. The method comprises the following steps: selecting pulping black liquor as a raw material, and mixing cyclohexane, n-amyl alcohol and an emulsifier to form a basic microemulsion; reacting a metal salt solution with the basic microemulsion to obtain microemulsion A; reacting an alkaline solution with the basic microemulsion to obtain microemulsion B; mixing the microemulsion A and the microemulsion B to obtain a microemulsion solid template; s3, uniformly mixing the solid template with pulping black liquor; heating, concentrating and drying to obtain a carbon precursor; s4, in an inert atmosphere, heating the carbon precursor according to two stages for carbonization and activation to form a blocky activated carbon intermediate material; s5, cooling and grinding into powder; and then carrying out acid pickling, water washing and drying to obtain an activated carbon product. All-component and high-value utilization of the pulping black liquor is achieved, the preparation process is simple, raw materials are low in price and easy to obtain, and the production cost is low.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and waste resource recycling technology, specifically a method for preparing an activated carbon adsorbent using pulping black liquor as raw material and hydroxide or carbonate microemulsion as a solid template. This adsorbent can achieve good removal of methylene blue under neutral conditions. Background Technology

[0002] Black liquor from pulping is an industrial waste liquid generated during the pulping process. It contains not only a large amount of lignin and some sugars, but also a large amount of alkaline pulping chemicals. It is characterized by high chemical oxygen demand (COD) and biological oxygen demand (BOD), strong alkalinity, low biodegradability, and dark color. If discharged directly without proper treatment, it will seriously harm aquatic organisms, lead to soil salinization, and hinder plant growth.

[0003] Currently, there are two main methods for treating black liquor: one is incineration to obtain heat energy and recover inorganic alkali. However, this method only makes low-value use of the abundant and valuable lignin resources and other organic components in black liquor. The other method is to extract lignin from black liquor, mainly through acid precipitation, ultrafiltration, enzyme treatment, and organic solvent treatment, to extract lignin from pulping black liquor and then convert the obtained lignin into high-value-added derivatives. Although these methods can recover lignin from black liquor, they generally suffer from high costs, long processing times, cumbersome operations, and the need for secondary wastewater treatment. Furthermore, acid precipitation consumes a large amount of acid, which not only depletes the inorganic alkali in the black liquor but also causes secondary pollution to the environment if the resulting secondary wastewater is not properly treated.

[0004] Although lignin extracted from black liquor can serve as a raw material for preparing high-value-added derivatives such as chemicals and functional polymers, its structure and properties vary significantly due to factors such as the source of pulping raw materials, pulping processes and conditions, and extraction methods. This greatly restricts the quality stability of derivatives that are highly dependent on the structure and properties of lignin, which is one of the main reasons why lignin extracted from black liquor is currently difficult to apply on a large scale.

[0005] Lignin is an aromatic compound with a high carbon content and high pyrolysis carbon yield, making it an ideal precursor for activated carbon production. Currently, the method for preparing activated carbon from pulping black liquor typically involves first extracting lignin from the black liquor using acid precipitation, followed by the addition of an activating agent or a process of carbonization followed by activation. While this method can utilize lignin to produce activated carbon, it consumes a large amount of acid during precipitation to neutralize the alkali in the black liquor, and then requires the addition of a large amount of alkali during activation. This approach is not only cumbersome, but also leaves the wastewater containing a certain amount of organic matter (including water-soluble low-molecular-weight lignin, sugars, and other organic matter) after lignin precipitation, requiring further treatment before discharge. This significantly increases the production cost of activated carbon, and the sugars and other organic matter in the black liquor, as well as the large amount of alkali, are not effectively utilized. For example, Chinese invention patent application CN113816374A discloses a method for preparing high-adsorption activated carbon using pulping black liquor. The method involves first concentrating the pulping black liquor, then adjusting it with cystine to form a solid intermediate product under acidic conditions, and finally sintering it in an inert atmosphere to obtain the carbonized product. This method requires the use of a large amount of alkaline solution for treatment, resulting in high reagent costs in the activated carbon production process.

[0006] Considering the characteristic of black liquor containing a large amount of organic components and inorganic alkalis or salts, directly carbonizing and activating activated carbon using the abundant carbon-containing organic matter, including lignin, in concentrated black liquor as a carbon source and the abundant inorganic alkalis (including sodium hydroxide, sodium carbonate, and sodium bicarbonate, etc.) as self-activating agents can not only convert carbon-containing organic matter such as lignin and sugars in black liquor into high-value-added activated carbon products, but also effectively utilize the abundant inorganic alkalis in black liquor, achieving full utilization of various components in black liquor. At the same time, it can eliminate the cumbersome lignin extraction process and the resulting secondary wastewater treatment problems, greatly simplifying the activated carbon preparation process and effectively reducing the production cost of activated carbon.

[0007] Currently, dye wastewater, as one of the major types of industrial wastewater, accounts for nearly 20% of the total industrial wastewater. More than 700,000 tons of dyes are produced annually, of which over 11% are directly discharged into water bodies. This dye wastewater is characterized by high chemical oxygen demand (COD), high color intensity, high pH value, and toxicity; direct discharge will cause irreversible damage to the ecological environment. Currently, activated carbon, with its large specific surface area, well-developed pore structure, and strong adsorption capacity, is mainly used as an adsorbent for treating dye wastewater. This method is low-cost, easy to operate, and highly efficient, making it the most effective and common approach for treating dye wastewater. However, the production cost of activated carbon suitable for adsorbing fuel wastewater is relatively high, which to some extent limits its application in treating fuel wastewater. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies in pulping black liquor treatment, such as secondary waste discharge and high cost of treatment reagents, and to provide a method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method and its application.

[0009] In a first aspect, the present invention provides a method for preparing activated carbon using black liquor self-activation combined with a microemulsion solid template method, achieving the goal of directly and efficiently preparing activated carbon from pulping black liquor. This reduces the cost of environmental treatment or resource utilization of pulping black liquor, while simultaneously achieving the production and processing of high-quality activated carbon.

[0010] A method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method includes the following steps: S1. Black liquor is selected as the raw material, and the solid content of the black liquor is ≥40 wt%; S2. Preparation of hydroxide or carbonate microemulsion solid template: Mix cyclohexane, n-pentanol and emulsifier to form a basic microemulsion; The metal salt solution was reacted with the basic microemulsion to obtain microemulsion A; The alkaline solution was reacted with the basic microemulsion to obtain microemulsion B; Microemulsion A and microemulsion B were mixed and reacted to obtain a microemulsion solid template; S3. Mix the microemulsion solid template with the pulping black liquor, stir and mix evenly; heat to concentrate, dry, and obtain carbon precursor; S4. Under an inert atmosphere, the carbon precursor is heated in two stages to carry out carbonization and activation treatment, forming blocky activated carbon intermediate material. S5. Cool the block activated carbon intermediate material and grind it into powder; then, perform acid washing, water washing and drying to obtain activated carbon product.

[0011] This invention provides a method for preparing activated carbon that utilizes a microemulsion solid template combined with lignin-rich pulping black liquor as the basic raw material. Lignin serves as the primary carbon source, and the inorganic alkali in the black liquor acts as a self-activating agent. Through carbonization and activation processes, the microemulsion solid template forms a porous structure. A two-stage heating method is used to form a blocky activated carbon intermediate material. This intermediate material is then acid-washed to remove alkaline salts, further increasing porosity. Finally, it is washed and dried to obtain an activated carbon product with high specific surface area and strong adsorption capacity. This method fully utilizes the inorganic alkali and lignin components in pulping black liquor, reducing reagent waste associated with multi-step synthesis methods. Furthermore, by fully leveraging the efficacy of various components in the pulping black liquor, the specific surface area of ​​the activated carbon is significantly superior to that obtained by other methods, resulting in a high-performance and low-cost activated carbon product.

[0012] The order of each step in the preparation method of this invention can be flexibly adjusted according to process requirements. Steps S1, S2, S3, S4, S5, etc. do not constitute an absolute limitation on the specific order.

[0013] Furthermore, the pulping black liquor is wastewater generated by the alkaline pulping process in the papermaking industry, containing carbonaceous organic matter and inorganic alkali, with a solid content ≥45 wt%.

[0014] Furthermore, the solid content of the pulping black liquor is ≥50 wt%. Pulping black liquor that has undergone concentration treatment has a higher solid content and is more suitable for activated carbon preparation, for example, a solid content of 58.8%.

[0015] Furthermore, the organic matter content in the pulping black liquor is ≥30 wt%. Preferably, the organic matter content is ≥34 wt%. For example, the organic matter content is 34.8%.

[0016] Furthermore, in S2, the mass ratio of cyclohexane, n-pentanol, and emulsifier is 1:(1-5):(2-10). Preparing the basic microemulsion with cyclohexane, n-pentanol, and emulsifier in the above ratio is more beneficial for the subsequent preparation of microemulsions A and B, resulting in a better performance of the microemulsion solid template obtained from their reaction.

[0017] Further, in S2, 1-5 parts by volume of metal salt solution are added dropwise to 10 parts by mass of the basic microemulsion and stirred until transparent to obtain microemulsion A.

[0018] In S2, 2-10 parts by volume of alkaline solution are added dropwise to 10 parts by mass of the basic microemulsion and stirred until colorless and transparent to obtain microemulsion B.

[0019] Mix 2-6 parts by volume of microemulsion A with 3-9 parts by volume of microemulsion B, and react to obtain a microemulsion solid template.

[0020] In cases involving the ratio of mass parts and volume parts, the mass parts are based on kilograms (kg) and the volume parts are based on liters (L). The conversion can be performed according to this unit relationship, as long as the proportion of parts remains constant.

[0021] Furthermore, the metal salt solution is a soluble salt solution of iron, magnesium, calcium, or copper with a concentration of 1-3 mol / L. Preferably, it is a salt solution of one or more of chlorides or nitrates.

[0022] Furthermore, the alkaline solution is an alkaline solution with a concentration of 4-6 mol / L, consisting of one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate.

[0023] Furthermore, in S2, the emulsifier is one or any combination of OP-10, Tween 80, or Span 80.

[0024] Furthermore, in S3, the mixing process of the microemulsion solid template and the pulping black liquor is as follows: 5-15 volume parts of the microemulsion solid template are added dropwise to 20 mass parts of the pulping black liquor while stirring, and stirring is continued for 15 minutes after the addition is completed.

[0025] Preferably, the microemulsion solid template is added slowly; more preferably, the adding rate is 1-20 mL / min.

[0026] Preferably, the stirring is vigorous stirring; more preferably, the stirring speed is ≥300 r / min; even more preferably, the stirring speed is ≥800 r / min.

[0027] Furthermore, in S3, the specific method for heating, concentrating, and drying to obtain the carbon precursor is as follows: first, heat the material to 60-90℃, concentrate it until the material hardens, and then dry it at 120-150℃ to obtain the carbon precursor.

[0028] Preferably, the method for obtaining the carbon precursor by heating, concentrating, and drying is as follows: first, heat the mixture to 80°C to concentrate and harden it, and then dry it at 140°C.

[0029] Furthermore, in S4, the carbon precursor is heated in two stages for carbonization and activation treatment, as detailed below: Under nitrogen protection, the carbon precursor is heated to 400-500℃ in the first stage and held for 1-3 hours; then the temperature is raised to 850-950℃ in the second stage and held for 1-4 hours to form blocky activated carbon intermediate material.

[0030] Preferably, the heating rate in the first stage is 1-10℃ / min, and the heating rate in the second stage is 2-15℃ / min.

[0031] Furthermore, in step S5, pickling involves soaking and washing with a hydrochloric acid solution to remove the template and inorganic salt impurities. Preferably, the concentration of the hydrochloric acid solution is 0.1-5 mol / L, more preferably 0.5-2 mol / L. For example, 1 mol / L. Other inorganic acids, such as sulfuric acid or nitric acid, can also be used.

[0032] After two stages of high-temperature heating treatment, the remaining material, blocky activated carbon intermediate material (activation material), is discharged as wastewater containing no organic matter, eliminating the need for secondary treatment of organic matter in the wastewater. This allows for the high-value utilization and full utilization of both organic and inorganic components in black liquor while eliminating black liquor pollution. More importantly, since the quality of the obtained activated carbon is largely unaffected by fluctuations in the structure and properties of lignin in black liquor, it enables large-scale industrial application of lignin from black liquor.

[0033] Furthermore, in S5, the water wash uses deionized water until the filtrate is neutral.

[0034] Furthermore, in step S5, drying is performed at 95-120°C for 3-24 hours. Preferably, drying is carried out at 100-115°C for 4-20 hours. For example, drying is carried out at 105°C for 12 hours.

[0035] In a second aspect, the present invention provides an application of the above-mentioned activated carbon in the adsorption treatment of dye wastewater. By enhancing the performance of activated carbon, better adsorption is achieved. Environmentally friendly activated carbon is produced using pulping black liquor for dye wastewater treatment, achieving an environmental protection effect close to "zero emissions".

[0036] The activated carbon product prepared by the above method is used to adsorb methylene blue in dye wastewater.

[0037] The activated carbon prepared by the above method of the present invention was used to adsorb methylene blue in dye wastewater. Experimental results showed that it had a large adsorption capacity and good adsorption effect.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention, starting from the characteristics of black liquor itself, uses organic carbonaceous substances, including lignin, in concentrated black liquor as a carbon source and various inorganic alkalis as self-activating agents. In-situ prepared microemulsion solid templates are added to the concentrated black liquor as mesoporous pore-forming agents. After uniform mixing and drying, activated carbon is directly carbonized and activated at high temperature. Compared with the traditional method of acid extraction of lignin followed by carbonization and activation to prepare activated carbon, this invention simplifies the production process, saves a significant amount of acid and alkali consumption, and avoids the post-treatment of secondary wastewater generated during acid precipitation, greatly reducing the production cost of activated carbon. While solving black liquor pollution, it achieves high-value utilization of all components in the black liquor. The entire activated carbon preparation process embodies the characteristics of being green, environmentally friendly, efficient, and utilizing all components of resources at high value.

[0039] 2. This invention, by adding in-situ prepared solid hydroxide or carbonate microemulsion templates as mesoporous pore-forming agents, can effectively regulate the pore structure of activated carbon, increase mesoporous porosity and specific surface area, thereby more efficiently adsorbing various organic dye molecules such as methylene blue in dye wastewater, and effectively reducing wastewater treatment costs. For example, the activated carbon prepared by this invention has abundant micropores and mesopores, resulting in a maximum specific surface area of ​​981 m². 2 With a mesoporous content of 68% and a maximum methylene blue adsorption capacity of 1084 mg / g, it exhibits excellent adsorption performance on dye wastewater and has great potential as an adsorbent.

[0040] 3. This invention provides a simple, easy, and efficient method for producing low-cost activated carbon adsorbents by directly using concentrated pulping black liquor wastewater as raw material without adding external activators. The resulting activated carbon is then used to adsorb dye wastewater, achieving the goal of "using waste to treat waste." This method solves environmental problems while utilizing waste resources, possessing not only good economic value but also significant social benefits.

[0041] 4. This invention utilizes both the carbon-containing organic components and the inorganic alkaline components in pulping black liquor, achieving full-component and high-value utilization of pulping black liquor. It has the advantages of simple activated carbon preparation process, inexpensive and readily available raw materials, and low production cost. Attached Figure Description

[0042] Figure 1 The image shows a scanning electron microscope (SEM) image of activated carbon prepared by combining black liquor from pulping with a nano-ferric hydroxide microemulsion solid template according to the present invention. The magnification is 20,000 times. The image shows that the prepared activated carbon has a rich pore structure.

[0043] Figure 2 The nitrogen adsorption-desorption isotherm (a) and pore size distribution diagram (b) of the activated carbon prepared by combining black liquor from pulping with nano-ferric hydroxide microemulsion solid template of the present invention are shown. It can be seen from the figure that the nitrogen adsorption-desorption isotherm is type IV with H3 type hysteresis loop, indicating that the prepared activated carbon has a large number of mesoporous structures. The pore size distribution diagram shows that there are corresponding microporous structures in the range of 0.4-2 nm. The results of the two figures show that the prepared activated carbon has layered microporous and mesoporous structures. Detailed Implementation

[0044] To address the shortcomings of existing technologies, this invention provides a method for preparing low-cost activated carbon using concentrated black liquor self-activation combined with microemulsion solid template, which is then applied to the adsorption of methylene blue. This solves the problems mentioned in the background technology, such as high cost of activated carbon preparation, cumbersome process, and the need for secondary wastewater treatment.

[0045] This invention uses concentrated black liquor from pulping as raw material, taking lignin and sugars, among other carbon-containing organic matter, as the carbon source, and abundant inorganic alkalis as self-activating agents. It also adds in-situ synthesized nano-hydroxide or carbonate microemulsion solid templates, mixes thoroughly, dries, and then directly carbonizes and activates at high temperature to form activated carbon rich in micropores and mesopores, with a large specific surface area and strong adsorption capacity. Compared to the process of acid precipitation to extract lignin and then preparing activated carbon, this method eliminates the cumbersome process of acid extraction of lignin from black liquor, saves a significant amount of acid and alkali, and enables the full utilization of organic carbon-containing components, including lignin and sugars, and inorganic alkalis (including sodium carbonate, sodium bicarbonate, and other salts) in black liquor. Furthermore, it eliminates the secondary wastewater treatment problem caused by acid extraction of lignin, greatly reducing the production cost of activated carbon. This invention solves the pollution caused by pulping black liquor, achieves the full-component, high-value utilization of black liquor resources, and produces low-cost activated carbon that can be applied to dye wastewater treatment, solving the problem of high treatment costs and achieving the goal of "using waste to treat waste."

[0046] This invention is characterized by its simplicity and ease of implementation, mild reaction conditions, low production cost, green and environmentally friendly production process, and significant effect on removing methylene blue from wastewater.

[0047] The method of the present invention can be briefly summarized as follows: a method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method, comprising the following steps: (1) At room temperature, cyclohexane, n-pentanol and emulsifier are mixed and stirred evenly in a mass ratio of 1:(1-5):(2-10) to obtain a transparent solution.

[0048] (2) Add 1-5 volumes of metal salt solution dropwise to 10 parts by mass of the solution obtained in step (1) and stir until a transparent microemulsion A is obtained. The mass parts are selected in kg / kg and the volume parts are selected in L / L. For example, 3 volumes of metal salt solution are selected in 3 liters, and the corresponding 10 parts by mass of the solution obtained in step (1) are selected in 10 kg.

[0049] (3) Add 2-10 parts by volume of alkaline solution dropwise to 10 parts by mass of the solution obtained in step (1), and stir until a colorless and transparent microemulsion B is obtained. The parts by mass are selected in kg / kg, and the parts by volume are selected in L / L.

[0050] (4) Add 2-6 volumes of the microemulsion A obtained in step (2) to 3-9 volumes of the microemulsion B obtained in step (3), and after mixing, a transparent hydroxide or carbonate microemulsion solid template is formed.

[0051] (5) Slowly add 5-15 parts by volume of the hydroxide or carbonate microemulsion solid template obtained in step (4) to 20 parts by mass of concentrated pulping black liquor while stirring vigorously. After all the hydroxide or carbonate microemulsion solid template has been added, stir for another 15 minutes. Then raise the temperature to 80°C until it is concentrated and hardened. Then dry it at 140°C and carbonize and activate it at high temperature under nitrogen protection. After cooling, grind it into powder. Soak and wash with 1 mol / L hydrochloric acid to remove the template, then wash with water until the filtrate is neutral. After drying, activated carbon is obtained.

[0052] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0053] In the following examples, the method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method, the mass parts are based on kilograms (kg) and the volume parts are based on liters (L).

[0054] Example 1 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and OP-10 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 1 volume part of a 1 mol / L ferric chloride solution was added to 10 parts by mass of the above transparent solution, and 2 volume parts of a 4 mol / L sodium hydroxide solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Two volume parts of the ferric chloride microemulsion and three volume parts of the sodium hydroxide microemulsion were added to a beaker to prepare a ferric hydroxide microemulsion solid template.

[0055] Add 5 parts by volume of ferric hydroxide microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0056] The mixture was then heated to 400℃ at a rate of 2℃ / min under nitrogen protection and held at that temperature for 2 hours, followed by cooling to room temperature. It was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. It was then dried at 105℃ to obtain activated carbon.

[0057] The activated carbon was tested and found to have a specific surface area of ​​18 m². 2 / g.

[0058] Weigh 0.05g of activated carbon sample and measure its adsorption capacity at 303K, pH=7, and methylene blue concentration of 600mg / L. The result is 37mg / g.

[0059] The methylene blue adsorption test method is as follows: Materials and reagents to be prepared: methylene blue (analytical grade), prepared activated carbon sample (ground and sieved, 100-200 mesh recommended), deionized water, volumetric flasks (100 mL, 1000 mL), conical flasks (with stopper, 250 mL), constant temperature shaker, UV-Vis spectrophotometer, centrifuge or 0.45 μm filter membrane, oven, analytical balance (accuracy 0.0001 g).

[0060] Accurately weigh 1.000 g of methylene blue, dissolve it in deionized water, and bring the volume to 1 L to obtain the methylene blue stock solution. Then, dilute the stock solution to working solutions with concentrations of 50, 100, 200, 400, 800, and 1000 mg / L. Measure the absorbance of the working solutions at 664 nm using a UV-Vis spectrophotometer. Plot a standard curve by fitting a linear regression equation with concentration on the x-axis and absorbance on the y-axis.

[0061] Weigh 0.05g of activated carbon sample, dry it at 105℃ to constant weight, and add it to 100 mL of methylene blue solution with a concentration of 600mg / L. Test the absorbance of the methylene blue solution after adsorption by activated carbon. Substitute the absorbance into the above standard curve to calculate the change in absorbance before and after adding activated carbon. Based on this, calculate the amount of absorbance reduction after methylene blue is adsorbed by activated carbon, and thus obtain the adsorption capacity of activated carbon sample for methylene blue.

[0062] Example 2 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Tween 80 were mixed and stirred until a clear solution was obtained. Then, 2 parts by volume of a 2 mol / L magnesium chloride solution were added to 10 parts by mass of the above clear solution, and 3 parts by volume of a 5 mol / L sodium hydroxide solution were added to another 10 parts by mass of the above clear solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Two parts by volume of the magnesium chloride microemulsion and three parts by volume of the sodium hydroxide microemulsion were added to a beaker to prepare a magnesium hydroxide microemulsion solid template.

[0063] Add 5 parts by volume of magnesium hydroxide microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0064] The carbon precursor was heated to 400℃ at 2℃ / min under nitrogen protection and held for 2h. It was then cooled to room temperature, ground into powder, washed with 1mol / L hydrochloric acid solution to remove template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. It was then dried at 105℃ to obtain activated carbon.

[0065] The specific surface area of ​​activated carbon is 23 m². 2 / g.

[0066] Following the test method of Example 1, 0.05 g of activated carbon sample was weighed and its adsorption capacity was measured to be 52 mg / g under the conditions of 303 K, pH=7 and methylene blue concentration of 600 mg / L.

[0067] Example 3 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Span 80 were mixed and stirred until a clear solution was obtained. Then, 3 parts by volume of a 2 mol / L calcium chloride solution were added to 10 parts by mass of the above clear solution, and 4 parts by volume of a 5 mol / L sodium carbonate solution were added to another 10 parts by mass of the above clear solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Two parts by volume of the calcium chloride microemulsion and three parts by volume of the sodium carbonate microemulsion were added to a beaker to prepare a calcium carbonate microemulsion solid template.

[0068] Add 5 parts by volume of calcium carbonate microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0069] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 1 hour. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0070] The specific surface area of ​​activated carbon is 801 m². 2 / g. Through a two-stage heat treatment under inert nitrogen protection, the carbon precursor was transformed into activated carbon with a larger specific surface area by undergoing two stages of heat treatment at 400℃ and 900℃. The corresponding activated carbon was fully activated, with abundant and fine pores, exhibiting a very large specific surface area. Compared with the activated carbon prepared in Examples 1 and 2, the specific surface area of ​​the material increased by 40-45 times, and the adsorption capacity was significantly enhanced.

[0071] The prepared activated carbon was tested using a scanning electron microscope, and the results are as follows: Figure 1 As shown in the image, at 20,000x magnification, the scanning electron microscope (SEM) image of the prepared activated carbon reveals a rich porous structure. The activated carbon exhibits well-developed and uniformly distributed pores, with a dense honeycomb-like pore structure on the surface. The pore morphology should be clear and regular, with good connectivity and no blockage. The branching and extension of the mesopores form a coral reef-like structure without collapse, making it suitable for liquid-phase applications such as water treatment.

[0072] The obtained activated carbon was further subjected to nitrogen adsorption and desorption tests, and the isotherm curves were obtained as follows: Figure 2 As shown in (a), the nitrogen adsorption-desorption isotherm curve is type IV with an H3 type hysteresis loop, indicating that the prepared activated carbon has a large number of mesoporous structures. The pore size distribution of the activated carbon was measured, and the results are as follows. Figure 2 As shown in (b), the pore size distribution diagram shows that microporous structures exist in the range of 0.4-2 nm. Figure 2 The test results in the two figures show that the prepared activated carbon has a layered microporous and mesoporous structure.

[0073] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 801mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0074] Example 4 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and OP-10 were mixed and stirred until a clear solution was obtained. Then, 4 volumes of a 3 mol / L copper nitrate solution were added to 10 parts by mass of the above clear solution, and 4 volumes of a 5 mol / L potassium hydroxide solution were added to another 10 parts by mass of the above clear solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Two volumes of the copper nitrate microemulsion and three volumes of the potassium hydroxide microemulsion were added to a beaker to prepare a copper hydroxide microemulsion solid template.

[0075] Add 5 parts by volume of copper hydroxide microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0076] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 1 hour. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0077] The specific surface area of ​​activated carbon is 769 m². 2 / g.

[0078] Following the test method of Example 1, 0.01 g of activated carbon sample was weighed and its adsorption capacity was measured to be 612 mg / g under the conditions of 303 K, pH=7 and methylene blue concentration of 1000 mg / L.

[0079] Example 5 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and OP-10 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 5 parts by volume of a 3 mol / L calcium chloride solution were added to 10 parts by mass of the above transparent solution, and 6 parts by volume of a 5 mol / L potassium carbonate solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Four parts by volume of the calcium chloride microemulsion and six parts by volume of the potassium carbonate microemulsion were added to a beaker to prepare a calcium carbonate microemulsion solid template.

[0080] 10 parts by volume of calcium carbonate microemulsion solid template were added to 20 parts by mass of concentrated pulping black liquor. The two raw materials were mechanically stirred at room temperature, and then stirred at 80°C until concentrated and hardened. The carbon precursor was obtained by drying at 140°C for 12 hours.

[0081] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 1.5 hours. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0082] The specific surface area of ​​activated carbon is 907 m². 2 / g.

[0083] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 923mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0084] Example 6 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and OP-10 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 2 parts by volume of a 2 mol / L ferric chloride solution were added to 10 parts by mass of the above transparent solution, and 3 parts by volume of a 5 mol / L ammonia solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Four parts by volume of the ferric chloride microemulsion and six parts by volume of the ammonia microemulsion were added to a beaker to prepare a ferric hydroxide microemulsion solid template.

[0085] Add 10 parts by volume of ferric hydroxide microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0086] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 2.5 hours. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0087] The specific surface area of ​​activated carbon is 981 m². 2 / g.

[0088] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 1084mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0089] Example 7 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Span 80 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 3 parts by volume of a 3 mol / L magnesium chloride solution were added to 10 parts by mass of the above transparent solution, and 5 parts by volume of a 6 mol / L ammonia solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Four parts by volume of the magnesium chloride microemulsion and six parts by volume of the ammonia microemulsion were added to a beaker to prepare a magnesium hydroxide microemulsion solid template.

[0090] Add 10 parts by volume of magnesium hydroxide microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0091] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 2 hours. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0092] The specific surface area of ​​activated carbon is 953 m². 2 / g.

[0093] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 987mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0094] Example 8 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Span 80 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 4 volumes of a 2 mol / L calcium chloride solution were added to 10 parts by mass of the above transparent solution, and 7 volumes of a 5 mol / L sodium carbonate solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions.

[0095] A calcium carbonate microemulsion solid template was prepared by adding 4 parts by volume of calcium chloride microemulsion and 6 parts by volume of sodium carbonate microemulsion to a beaker.

[0096] 10 parts by volume of calcium carbonate microemulsion solid template were added to 20 parts by mass of pulping black liquor. The two raw materials were mechanically stirred at room temperature, and then stirred at 80°C until concentrated and hardened. The carbon precursor was dried at 140°C for 12 hours. The temperature was then increased to 400°C at 2°C / min and held for 2 hours under nitrogen protection, and then increased to 900°C at 5°C / min and held for 2 hours. The precursor was then cooled to room temperature, ground into powder, washed with 1 mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The precursor was dried at 105°C to obtain activated carbon.

[0097] Specific surface area is 978 m² 2 / g of activated carbon.

[0098] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 1011mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0099] Example 9 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Span 80 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 5 parts by volume of a 1 mol / L copper chloride solution were added to 10 parts by mass of the above transparent solution, and 10 parts by volume of a 2 mol / L sodium hydroxide solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Six parts by volume of the copper chloride microemulsion and nine parts by volume of the sodium hydroxide microemulsion were added to a beaker to prepare a copper hydroxide microemulsion solid template.

[0100] 15 parts by volume of calcium hydroxide microemulsion solid template were added to 20 parts by mass of concentrated pulping black liquor. The two raw materials were mechanically stirred at room temperature, and then stirred at 80°C until concentrated and hardened. The carbon precursor was obtained by drying at 140°C for 12 hours.

[0101] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 1.5 hours. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0102] The specific surface area of ​​activated carbon is 827 m². 2 / g.

[0103] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 874mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0104] Example 10 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Tween 80 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 4 volumes of a 2 mol / L ferric chloride solution were added to 10 parts by mass of the above transparent solution, and 6 volumes of a 5 mol / L potassium hydroxide solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. A ferric chloride microemulsion solid template was prepared by adding 6 volumes of the ferric chloride microemulsion and 9 volumes of the sodium hydroxide microemulsion to a beaker.

[0105] Add 15 parts by volume of ferric hydroxide microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0106] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 2.5 hours. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0107] The specific surface area of ​​activated carbon is 859 m². 2 / g.

[0108] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 915mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0109] Example 11 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Tween 80 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 2 parts by volume of a 3 mol / L magnesium chloride solution were added to 10 parts by mass of the above transparent solution, and 8 parts by volume of a 6 mol / L potassium carbonate solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Four parts by volume of the magnesium chloride microemulsion and six parts by volume of the potassium carbonate microemulsion were added to a beaker to prepare a magnesium carbonate microemulsion solid template.

[0110] Add 15 parts by volume of magnesium carbonate microemulsion solid template to 20 parts by mass of concentrated pulping black liquor. Mechanically stir the two raw materials at room temperature, then stir at 80°C until concentrated and hardened, and dry at 140°C for 12 hours to obtain carbon precursor.

[0111] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 3 hours. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0112] Specific surface area is 838 m² 2 / g.

[0113] Weigh 0.01g of activated carbon sample and measure its adsorption capacity at 303K, pH=7, and methylene blue concentration of 1000mg / L. The result is 906mg / g.

[0114] Example 12 A method for preparing activated carbon using black liquor self-activation combined with microemulsion template method and its application in adsorbing methylene blue, the specific process steps are as follows: Cyclohexane, n-pentanol, and Tween 80 were mixed and stirred until homogeneous to obtain a transparent solution. Then, 3 parts by volume of a 1 mol / L calcium chloride solution were added to 10 parts by mass of the above transparent solution, and 9 parts by volume of a 6 mol / L potassium carbonate solution were added to another 10 parts by mass of the above transparent solution. The mixtures were stirred until homogeneous to obtain two water-in-oil microemulsions. Six parts by volume of the calcium chloride microemulsion and nine parts by volume of the potassium carbonate microemulsion were added to a beaker to prepare a calcium carbonate microemulsion solid template.

[0115] 15 parts by volume of calcium carbonate microemulsion solid template were added to 20 parts by mass of concentrated pulping black liquor. The two raw materials were mechanically stirred at room temperature, and then stirred at 80°C until concentrated and hardened. The carbon precursor was obtained by drying at 140°C for 12 hours.

[0116] Under nitrogen protection, the temperature was increased to 400℃ at 2℃ / min and held for 2 hours, then increased to 900℃ at 5℃ / min and held for 3 hours. After cooling to room temperature, the powder was ground into powder, washed with 1mol / L hydrochloric acid solution to remove the template and other inorganic salt impurities, and then washed repeatedly with deionized water until the filtrate was neutral. The powder was then dried at 105℃ to obtain activated carbon.

[0117] The specific surface area of ​​activated carbon is 833 m². 2 / g.

[0118] Referring to the test method in Example 1, 0.01g of activated carbon sample was weighed and its adsorption capacity was measured to be 896mg / g under the conditions of 303K, pH=7 and methylene blue concentration of 1000mg / L.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0120] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer," etc., used in the description of specific embodiments of the present invention to indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0121] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0122] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0123] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0124] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

Claims

1. A method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method, characterized in that, Includes the following steps: S1. Black liquor is selected as the raw material, and the solid content of the black liquor is ≥40 wt%; S2. Preparation of hydroxide or carbonate microemulsion solid template: Mix cyclohexane, n-pentanol and emulsifier to form a basic microemulsion; The metal salt solution was reacted with the basic microemulsion to obtain microemulsion A; The alkaline solution was reacted with the basic microemulsion to obtain microemulsion B; Microemulsion A and microemulsion B were mixed and reacted to obtain a microemulsion solid template; S3. Mix the microemulsion solid template with the pulping black liquor and stir until the mixture is homogeneous; The carbon precursor is obtained by heating, concentrating, and drying. S4. Under an inert atmosphere, the carbon precursor is heated in two stages to carry out carbonization and activation treatment, forming blocky activated carbon intermediate material. S5. Cool the block activated carbon intermediate material and grind it into powder; then, perform acid washing, water washing and drying to obtain activated carbon product.

2. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 1, characterized in that, The pulping black liquor is wastewater generated from the alkaline pulping process in the papermaking industry. It contains carbonaceous organic matter and inorganic alkali, and its solid content is ≥45 wt%. The organic matter content in the pulping black liquor is ≥30 wt%.

3. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 1, characterized in that, In S2, the mass ratio of cyclohexane, n-pentanol, and emulsifier is 1:(1-5):(2-10); Add 1-5 parts by volume of metal salt solution dropwise to 10 parts by mass of the basic microemulsion and stir until transparent to obtain microemulsion A; Add 2-10 parts by volume of alkaline solution dropwise to 10 parts by mass of the basic microemulsion and stir until colorless and transparent to obtain microemulsion B; Mix 2-6 parts by volume of microemulsion A with 3-9 parts by volume of microemulsion B, and react to obtain a microemulsion solid template; In cases involving the ratio of mass parts and volume parts, the mass parts are based on kilograms, and the volume parts are based on liters.

4. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 3, characterized in that, The metal salt solution is a soluble iron, magnesium, calcium or copper salt solution with a concentration of 1-3 mol / L; The alkaline solution is an alkaline solution with a concentration of 4-6 mol / L, consisting of one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate. The emulsifier is one or any combination of OP-10, Tween 80 or Span 80.

5. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 1, characterized in that, In S3, the mixing process of the microemulsion solid template and the pulping black liquor is as follows: 5-15 volume parts of the microemulsion solid template are added dropwise to 20 mass parts of the pulping black liquor while stirring. After the addition is completed, stirring is continued for 15 minutes.

6. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 5, characterized in that, The microemulsion solid template was added at a rate of 1-20 mL / min; the stirring was vigorous, with a stirring speed ≥300 r / min.

7. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 1, characterized in that, In S3, the specific method for obtaining carbon precursor by heating, concentration and drying is as follows: first, heat the material to 60-90℃, concentrate it until the material hardens, and then dry it at 120-150℃ to obtain carbon precursor.

8. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 1, characterized in that, In S4, the carbon precursor is heated in two stages for carbonization and activation treatment, as detailed below: Under nitrogen protection, the carbon precursor is heated to 400-500℃ in the first stage and held for 1-3 hours; then the temperature is raised to 850-950℃ in the second stage and held for 1-4 hours to form block activated carbon intermediate material. The heating rate in the first stage is 1-10℃ / min; the heating rate in the second stage is 2-15℃ / min.

9. The method for preparing activated carbon using black liquor self-activation combined with microemulsion solid template method according to claim 1, characterized in that, In step S5, pickling is performed by soaking and washing with a hydrochloric acid solution; the concentration of the hydrochloric acid solution is 0.1-5 mol / L. Wash with deionized water until the filtrate is neutral. Drying is carried out at 95-120℃ for 3-24 hours.

10. The application of the activated carbon product prepared by the method according to any one of claims 1-9 in the adsorption of methylene blue in dye wastewater.

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