Preparation method of porous carbon adsorption material and application thereof

Abstract

This invention belongs to the technical field of water pollution control and solid waste resource utilization, specifically relating to a method for preparing porous carbon adsorbent materials and their application. The method includes the following steps: S1, pretreating carbon-containing biomass solid waste and calcium-containing industrial solid waste respectively to obtain pretreated biomass material and pretreated calcium-containing solid waste; S2, immersing the pretreated biomass material in an iron-based modifier system for modification treatment to obtain iron-based modified biomass material; S3, mixing the iron-based modified biomass material and the pretreated calcium-containing solid waste evenly to obtain a catalytic precursor; S4, subjecting the catalytic precursor to programmed temperature co-pyrolysis treatment, and obtaining a primary pyrolysis product after cooling; S5, sequentially subjecting the primary pyrolysis product to water washing, solid-liquid separation, drying, and pulverization to obtain the porous carbon adsorbent material. The raw materials of this invention are widely available and inexpensive, the preparation process is simple and can be mass-produced, and the overall cost is significantly lower than that of ordinary commercial activated carbon.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control and solid waste resource utilization technology, specifically relating to a method for preparing porous carbon adsorbent materials and their application. Background Technology

[0002] Rhodamine B, a typical triphenylmethane basic dye, is widely used in textile dyeing, printing, fluorescent probes, and biological dyeing. This dye is characterized by high chemical stability, poor biodegradability, potential toxicity, and carcinogenicity. If the wastewater generated during its production and use is discharged directly without effective treatment, it will lead to excessive color and decreased light transmittance in water bodies, disrupting the material cycle and energy flow of aquatic ecosystems. Furthermore, it poses a potential threat to human health through bioaccumulation in the food chain. Therefore, developing efficient and economical Rhodamine B wastewater treatment technologies has become an important research direction in the environmental field.

[0003] Currently, the mainstream technologies for treating Rhodamine B in water include adsorption, photocatalytic degradation, coagulation and flocculation, and ozone oxidation. Among these, adsorption is considered the preferred technology for large-scale application due to its advantages such as simple operation, low operating cost, no secondary pollution, and the ability to enrich and recover pollutants. However, existing adsorption materials still face many technical bottlenecks: high-performance adsorbents such as carbon nanotubes and MOF-derived carbon materials are expensive to prepare and highly dependent on raw materials, making it difficult to achieve large-scale engineering applications; traditional activated carbon has a limited specific surface area and a simple pore structure, making it difficult to meet the adsorption capacity and rate of Rhodamine B for complex wastewater treatment needs; single biomass carbon materials lack desulfurization or dechlorination functions, making them unsuitable for treating complex industrial wastewater containing sulfur, thus limiting their application scenarios. At the same time, the large amount of desulfurization ash generated during the flue gas desulfurization process in steel enterprises, if arbitrarily piled up, can easily cause secondary pollution of soil and groundwater; the resource utilization rate of biomass solid waste such as bean stalks generated in agricultural production is low, and large-scale incineration or landfill not only wastes resources but also exacerbates the pressure on air and solid waste disposal.

[0004] Furthermore, the preparation of existing biomass carbon materials largely relies on traditional pyrolysis furnaces and muffle furnaces, which suffer from high energy consumption, low thermocatalytic efficiency, and insufficient precision in process parameter control, making it difficult to achieve precise control of pore structure. The optimization of the ratio of biomass to industrial solid waste in co-thermal catalysis lacks systematic research, resulting in a difficulty in simultaneously achieving optimal pore structure and adsorption performance, and hindering the synergistic improvement of desulfurization function and cycle stability. Therefore, developing a composite porous carbon material based on highly efficient thermocatalytic equipment to achieve the co-resource utilization of agricultural and industrial solid waste, possessing high adsorption capacity, desulfurization function, and excellent cycle stability, is of significant practical importance for solving the dual challenges of Rhodamine B wastewater treatment and solid waste disposal, and promoting the coordinated development of environmental governance and resource recycling. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing porous carbon adsorbent materials and their applications, overcoming the shortcomings of existing technologies. Using agricultural waste (bean stalks) and industrial solid waste (desulfurization ash) as main raw materials, combined with conventional industrial-grade ferric sulfate as a modifier, the raw materials are widely available and inexpensive. The preparation process is simple and can be scaled up, significantly reducing the overall cost compared to ordinary commercial activated carbon. This invention proposes an activated porous carbon material with both high adsorption capacity and desulfurization loading function, achieving synergistic resource utilization of agricultural waste (bean stalks) and industrial solid waste (desulfurization ash), while simultaneously achieving efficient and stable adsorption and removal of Rhodamine B from water.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions: A method for preparing a porous carbon adsorbent material according to the present invention includes the following steps:

[0008] S1. Raw material pretreatment: Carbon-containing biomass solid waste and calcium-containing industrial solid waste are pretreated to obtain pretreated biomass material and pretreated calcium-containing solid waste. The raw material pretreatment in S1 includes impurity removal, washing, drying, and crushing. The carbon-containing biomass solid waste is agricultural biomass solid waste, and the calcium-containing industrial solid waste is at least one of calcium sulfate solid waste and carbonate solid waste. The calcium sulfate solid waste is desulfurization ash, and the calcium carbonate solid waste is marble waste powder.

[0009] S2, Iron-based modification: The pretreated biomass is immersed in an iron-based modifier system for modification to obtain iron-based modified biomass. The iron-based modification in S2 is a liquid-solid phase impregnation and stirring modification, and the modification process includes a continuous process of impregnation, stirring reaction, solid-liquid separation, washing, and drying. The iron-based modifier system in S2 is an aqueous solution of ferric sulfate; the material-to-liquid ratio of the impregnation is the mass-to-volume ratio of the pretreated biomass to the aqueous solution of ferric sulfate 1 g:(5~20) mL, and the stirring reaction time is 2~6 h.

[0010] S3. Raw material mixing: The iron-based modified biomass material and the pretreated calcium-containing solid waste are mixed evenly to obtain a catalytic precursor; the mixing mass ratio of the iron-based modified biomass material and the pretreated calcium-containing solid waste in S3 is 7~9:1~3. Preferably, the specific steps of raw material mixing in S3 are as follows: weigh the iron-based modified biomass material and the pretreated calcium-containing solid waste at a mass ratio of 8:2, put them into a high-speed mixer and stir to obtain a uniformly mixed thermal catalytic raw material.

[0011] S4. Co-pyrolysis: The catalytic precursor is subjected to programmed temperature co-pyrolysis, during which iron-based catalytic pore formation and calcium-based loading are simultaneously coupled. After cooling, the primary pyrolysis product is obtained. The co-pyrolysis cooling process in S4 is carried out under a continuously supplied protective gas atmosphere. During the formation of iron-based channels, the calcium-based component is simultaneously and in situ loaded onto the surface and within the porous carbon framework. The heating rate of the programmed temperature co-pyrolysis in S4 is 5~10℃ / min, the final co-pyrolysis temperature is 650~800℃, and the isothermal co-pyrolysis time is 1~3h. The cooling is natural cooling to room temperature.

[0012] S5. Post-processing: The primary pyrolysis product is sequentially washed with water, separated from solids and liquids, dried and pulverized to obtain the porous carbon adsorbent material.

[0013] Furthermore, in S1, the carbon-containing biomass solid waste selected is large-scale agricultural waste bean stalks with a moisture content of ≤25% and free from mold. Impurities are removed by a drum-type impurity remover, and the stalks are rinsed three times with deionized water in a high-pressure spray washing line. They are then dried to a moisture content of ≤3% by a mesh belt dryer at 105±5℃. The stalks are then pulverized to a particle size of <0.178mm by a two-stage pulverizing system and screened through an 80-mesh vibrating screen. The material passing through the screen is bean stalk powder, while the material passing through the screen is returned to the two-stage pulverizing system for reprocessing.

[0014] Further, in step S4, soybean stalk powder (pretreated biomass) is immersed in a 0.5-2 mol / L industrial-grade ferric sulfate solution and stirred for 2-6 hours in a continuous stirred reactor at 60±3℃ and 300 r / min. The precipitate is collected by filtration using a plate and frame filter press, and washed with deionized water using a countercurrent washing device until the conductivity of the washing liquid is ≤50 μS / cm. The powder is then dried in a chamber dryer at 105±5℃ until the moisture content is ≤3%, yielding ferric sulfate-modified soybean stalk powder (iron-based modified biomass) with an iron content of 3-5 wt%. Preferably, the optimal flow rate of nitrogen in step S4 is 80 mL / min; the optimal heating rate is 8℃ / min; the optimal thermocatalytic temperature is 750℃; and the optimal thermocatalytic time is 2 hours.

[0015] Further, in S3, the catalytic precursor is placed in a high-speed mixer and stirred at 300 r / min for 15 to 30 min to obtain a uniformly mixed thermal catalytic feedstock.

[0016] Further, in S4, the thermal catalytic raw material is evenly spread in a quartz boat and fed into a self-made carbon-based solid waste thermal catalytic furnace. Nitrogen gas is introduced as a protective gas, and the nitrogen flow rate is controlled at 50~100mL / min. The temperature is raised to 650~800℃ at a heating rate of 5~10℃ / min, and the thermal catalysis is carried out at a constant temperature for 1~3h. The heating device is turned off, and nitrogen gas is kept introduced until the furnace cools down to room temperature naturally to obtain the thermal catalytic primary product.

[0017] Further, in S5, the primary product of thermal catalysis is placed in a beaker, deionized water is added and stirred and washed for 10 min, vacuum filtered and the washing operation is repeated until the pH of the filtrate is neutral, the filter residue is dried in an oven at 105℃ for 8 h, pulverized and passed through a 120 mesh sieve to obtain the soybean straw-based active porous carbon material (porous carbon adsorbent material) loaded with desulfurization.

[0018] Technical Solution Two: A porous carbon adsorbent material, prepared by the above-described preparation method; the material has a hierarchical pore structure formed by iron-based catalysis, and calcium-based components are in situ loaded on the pore surface and framework.

[0019] Furthermore, the material has a BET specific surface area ≥388.1m² / g, a total pore volume ≥0.8cm³ / g, and a mesoporous pore volume ratio ≥65%.

[0020] Technical Solution 3: Application of a porous carbon adsorbent material in wastewater treatment, wherein the porous carbon adsorbent material described above is added to the water body to be treated to achieve simultaneous removal of dye pollutants and sulfides or chlorides in the water body.

[0021] Further, the application specifically includes the following steps: adding the active porous carbon material to water containing Rhodamine B, adjusting the pH of the water to 2~10, and adsorbing it at 200r / min for 30~180min at room temperature; the maximum adsorption capacity of the material for Rhodamine B is ≥481.5mg / g, and the removal rate of sulfides in the water is ≥85%.

[0022] Furthermore, after seven adsorption-desorption cycles, the porous carbon adsorbent material still maintains more than 80% of its initial adsorption performance for Rhodamine B.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. Significantly enhanced selective adsorption capacity: Through iron-based catalytic pore formation, a multi-level pore structure is formed. BET analysis shows that the proportion of micropores is high. The narrow pores (<2 nm) preferentially retain Rhodamine B (RhB) molecules through size sieving effect, while effectively suppressing the interference of competing ions such as Cl⁻ and SO4²⁻. This makes the material's selective adsorption capacity in complex water bodies far exceed that of traditional biomass carbon and single modified materials.

[0025] 2. Significantly optimized adsorption kinetics: The adsorption process conforms to the pseudo-second-order kinetic model, with chemisorption as the dominant process. Adsorption equilibrium can be reached within 240 minutes, and the adsorption efficiency is more than 40% higher than that of the unmodified material, meeting the engineering requirements for high-efficiency wastewater treatment.

[0026] 3. Dual-function synergy adapts to complex scenarios: It achieves the synergistic function of efficient adsorption of Rhodamine B and simultaneous removal of sulfides, with a removal rate of over 85% for sulfides in water. This breaks through the functional limitations of single adsorption materials and can be directly applied to complex industrial wastewater treatment scenarios containing sulfur.

[0027] 4. Significantly enhanced cycle stability: After seven adsorption-desorption cycles, the material's adsorption performance for Rhodamine B remained above 80% of its initial value. The stable composite structure formed by the iron oxide and desulfurization ash components effectively inhibited the collapse of the carbon framework and the loss of active sites, greatly improving the material's service life and recyclability.

[0028] 5. Maximize the utilization rate of solid waste resources: Achieve 100% resource utilization of agricultural waste bean stalks and industrial solid waste desulfurization ash, which not only reduces the resource waste and environmental pressure caused by agricultural solid waste incineration and landfill, but also solves the secondary pollution problem caused by desulfurization ash storage, which is in line with the concept of circular economy development.

[0029] 6. Excellent environmental adaptability and anti-interference ability: The material exhibits stable adsorption performance and strong anti-interference ability within a wide pH range of 2 to 10. It can be directly applied to the treatment of Rhodamine B wastewater with different acidities without the need for additional pH adjustment, which significantly reduces the process operating cost and operational complexity.

[0030] 7. Outstanding economic benefits and energy conservation and emission reduction benefits:

[0031] 1) The raw materials are inexpensive and widely available. The preparation process uses continuous thermocatalytic equipment, which reduces energy consumption by more than 30% compared with the traditional activated carbon preparation process.

[0032] 2) The combustible components recovered during the thermocatalytic process can be used as an auxiliary heat source to further reduce energy consumption;

[0033] 3) High material recycling rate reduces the amount of fresh materials required, thereby lowering wastewater treatment operating costs;

[0034] 4) The utilization of solid waste resources reduces greenhouse gas emissions and has both carbon capture and emission reduction effects.

[0035] 8. Significant achievements in the high-value transformation of renewable resources: Breaking through the bottleneck of traditional low-value utilization of agricultural biomass such as soybean stalks, the "modification-thermal catalysis" synergistic process transforms them into functional materials with high specific surface area and high adsorption performance, thereby increasing the added value of resources. This provides a replicable technical path for the large-scale high-value utilization of agricultural renewable resources and promotes the upgrading of the agricultural waste resource utilization industry.

[0036] 9. Cost Reduction and Efficiency Improvement through Co-processing of Industrial Solid Waste: No complex pretreatment of desulfurization ash is required; it can be directly combined with soybean straw for co-thermal catalysis to provide structural support and enhance desulfurization function. The disposal cost per ton of desulfurization ash can be reduced. Simultaneously, the complementary nature of the components among the solid wastes optimizes product performance, achieving the dual benefits of "treating waste with waste and complementary waste-to-waste processes."

[0037] 10. Enhanced stability and resilience of the raw material supply chain: Renewable agricultural solid waste (bean stalks) accounts for 80% of the raw material system, while industrial solid waste (desulfurization ash) accounts for 20%, significantly reducing reliance on non-renewable mineral resources. Both raw materials are regionally stable solid waste resources, enabling "local sourcing and on-site conversion," reducing costs and carbon emissions from cross-regional transportation of raw materials, and enhancing the stability of the production supply chain.

[0038] 11. Promote the coordinated development of the cross-industry solid waste resource utilization industrial chain: Large-scale application can drive the coordinated development of agricultural waste collection, storage and transportation systems and industrial solid waste harmless disposal industries, forming a closed-loop industrial chain of "solid waste collection - processing - high-value products - wastewater treatment - recycling". On the one hand, it provides solid waste disposal solutions for agricultural production areas, and on the other hand, it opens up new resource utilization paths for desulfurization ash from coal-fired power plants, promotes the construction of a cross-industry solid waste collaborative disposal industrial ecosystem, and helps form a green and low-carbon industrial cluster.

[0039] 12. When using marble waste powder, the dechlorination activity is enhanced, and the dechlorination efficiency and adsorption capacity are improved: This invention modifies the powder by impregnation with ferric sulfate solution, so that the iron-based component is chemically combined with the oxygen-containing functional groups of the bean stalk, avoiding the problems of low catalytic efficiency and component loss caused by conventional physical mixing; at the same time, the iron-based component not only undertakes the catalytic pore-forming function, but also serves as an auxiliary dechlorination active site, forming a synergistic dechlorination system with the calcium-based active sites (CaO) generated by the pyrolysis of marble waste powder. This significantly increases the number of active sites on the material surface, enhances the adsorption affinity for residual chlorine, and greatly improves the dechlorination efficiency and saturated adsorption capacity, which can meet the dechlorination needs of drinking water, industrial circulating water and other fields.

[0040] 13. Improve material stability and regeneration performance, and extend service life: The introduction of marble waste powder not only provides calcium-based active sites, but also enhances the mechanical strength and chemical stability of the dechlorination material, reducing material loss during use; at the same time, the calcium-based active component achieves "in-situ loading" through co-thermal catalysis, replacing the conventional "post-mixing loading", significantly improving the binding stability of the active component and the carbon support, solving the problems of easy detachment of active components and poor cycle performance of existing supported dechlorination materials, and maintaining high dechlorination activity after multiple adsorption-desorption cycles, extending the service life of the material and reducing the actual application cost. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a process for preparing a porous carbon adsorbent material.

[0042] Figure 2 SEM images of porous carbon adsorbent materials: a) SEM image of soybean straw biochar; b) SEM image of ferric sulfate-modified active porous carbon; c) SEM image of active porous carbon loaded with desulfurization ash; d) SEM image of active porous carbon material loaded with desulfurization ash and modified with ferric sulfate.

[0043] Figure 3 The adsorption kinetic parameters for Rhodamine B by porous carbon adsorbents are shown. a represents the pseudo-first-order kinetic curve; b represents the pseudo-second-order kinetic curve.

[0044] In the diagram, 1: soybean stalk raw material silo; 2: vertical crusher; 3: ferric sulfate solution continuous stirring reaction tank;

[0045] 4: Desulfurization ash drying and pulverizing; 5: High-speed mixer; 6: Quartz boat + carbon-based solid waste thermal catalytic furnace;

[0046] 7: Vacuum Filter Drying Oven. Detailed Implementation

[0047] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0048] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some embodiments of the present invention. For those skilled in the art, other specific embodiments can be obtained based on these specific embodiments without creative effort.

[0049] The components of the embodiments of the invention described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the specific embodiments is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0050] The present invention provides a method for preparing a porous carbon adsorbent material, comprising the following steps:

[0051] S1. Raw material pretreatment: Carbon-containing biomass solid waste and calcium-containing industrial solid waste are pretreated to obtain pretreated biomass material and pretreated calcium-containing solid waste; the raw material pretreatment in S1 includes impurity removal, washing, drying and crushing; the carbon-containing biomass solid waste is agricultural biomass solid waste, and the calcium-containing industrial solid waste is calcium sulfate solid waste or calcium carbonate solid waste.

[0052] S2, Iron-based modification: The pretreated biomass is immersed in an iron-based modifier system for modification to obtain iron-based modified biomass. The iron-based modification in S2 is a liquid-solid phase impregnation and stirring modification, and the modification process includes a continuous process of impregnation, stirring reaction, solid-liquid separation, washing, and drying. The iron-based modifier system in S2 is an aqueous solution of ferric sulfate; the material-to-liquid ratio of the impregnation is the mass-to-volume ratio of the pretreated biomass to the aqueous solution of ferric sulfate 1 g:(5~20) mL, and the stirring reaction time is 2~6 h.

[0053] S3. Raw material mixing: The iron-based modified biomass and the pretreated calcium-containing solid waste are mixed evenly to obtain a catalytic precursor. The specific steps of raw material mixing in S3 are as follows: iron-based modified biomass and pretreated calcium-containing solid waste are weighed at a mass ratio of 8:2 and placed in a high-speed mixer for stirring to obtain a uniformly mixed thermocatalytic raw material. The mass ratio of iron-based modified biomass to pretreated calcium-containing solid waste in S3 is 7~9:1~3; the inert gas is nitrogen, and the nitrogen flow rate is 50~100 mL / min.

[0054] S4. Co-pyrolysis: The catalytic precursor is subjected to programmed temperature co-pyrolysis, during which iron-based catalytic pore formation and calcium-based loading are simultaneously coupled. After cooling, the primary pyrolysis product is obtained. The co-pyrolysis cooling process in S4 is carried out under a continuously supplied protective gas atmosphere. During the formation of iron-based channels, the calcium-based component is simultaneously and in situ loaded onto the surface and within the porous carbon framework. The heating rate of the programmed temperature co-pyrolysis in S4 is 5~10℃ / min, the final co-pyrolysis temperature is 650~800℃, and the isothermal co-pyrolysis time is 1~3h. The cooling is natural cooling to room temperature.

[0055] S5. Post-processing: The primary pyrolysis product is sequentially washed with water, separated from solids and liquids, dried and pulverized to obtain the porous carbon adsorbent material.

[0056] In this embodiment of the invention, the carbon-containing biomass solid waste selected is bean stalks, a large-scale agricultural waste with a moisture content ≤25% and free from mold. Alternatively, corn stalks, wheat stalks, rice stalks, peanut shells, and walnut shells can also be selected. The calcium sulfate-containing solid waste is selected from at least one of desulfurization ash, industrial by-product gypsum, phosphogypsum, and titanium gypsum. This embodiment uses desulfurization ash, a by-product of flue gas desulfurization in coal-fired power plants, as an example of calcium sulfate-containing solid waste. However, in other embodiments of this application, calcium carbonate-containing solid waste can also be selected for chlorination removal, such as at least one of marble waste powder, limestone tailings, and calcite waste residue. This invention uses marble waste powder as an example for chlorination removal. If marble waste powder is used, it is prepared by the following method: First, the marble waste powder is placed in a forced-air drying oven and dried at 105℃ for 2 hours. After drying, stones and impurities are removed. After drying, the marble waste powder is crushed by a vertical ring mill and screened by a vibrating screen. It is then passed through an 80-mesh standard inspection sieve. The material that passes through the sieve is purified marble waste powder and placed in a desiccator for later use.

[0057] In a desulfurization application of the porous carbon adsorption material of the present invention.

[0058] Example 1

[0059] 1. Sample preparation:

[0060] A method for preparing porous carbon adsorbent material samples includes the following steps:

[0061] S1. Select agricultural waste bean stalks, remove impurities, rinse with deionized water, remove impurities using a drum-type impurity remover, rinse three times with deionized water in a high-pressure spray washing line, dry with a mesh belt dryer at 105±5℃ until the moisture content is ≤3%, and pulverize to a particle size <0.178mm using a two-stage pulverizing system. The material is then screened through an 80-mesh vibrating screen. The material that passes through the screen is bean stalk powder, and the material that passes through the screen is returned to the two-stage pulverizing system for reprocessing.

[0062] Desulfurization ash (containing ≥70% CaSO4・2H2O) is selected as a byproduct of flue gas desulfurization in coal-fired power plants. It is dried in a disc dryer at 105±5℃ for 2 hours until the moisture content is ≤2%. After being crushed by a vertical pulverizer, it is screened through a 120-mesh vibrating screen. The undersize material is sealed and stored for later use.

[0063] S2. This example illustrates the process of immersing bean stalk powder in a 1 mol / L industrial-grade ferric sulfate solution at a solid-liquid ratio of 1 g: 10 mL. The mixture is stirred and modified in a continuous stirred reactor at 60±3℃ and 300 r / min for 4 h. The precipitate is collected by filtration using a plate and frame filter press and washed with deionized water using a countercurrent washing device until the conductivity of the washing liquid is ≤50 μS / cm. After filtration and washing three times, the mixture is dried in a chamber dryer at 105±5℃ until the moisture content is ≤3%, yielding ferric sulfate modified bean stalk powder (i.e., iron-based modified biomass) with an iron content of 3~5 wt%.

[0064] S3. Weigh 80g of ferric sulfate modified bean stalk powder and 20g of desulfurization ash, a byproduct of flue gas desulfurization from a coal-fired power plant treated by S1, and put them into a high-speed mixer and stir at 300r / min for 20min to obtain a uniformly mixed thermal catalytic raw material.

[0065] S4. The thermal catalytic raw material is spread on a quartz boat and fed into a self-made thermal catalytic furnace. Nitrogen gas is introduced as a protective gas and the nitrogen flow rate is controlled at 80 mL / min. The temperature is raised to 750℃ at a rate of 8℃ / min and kept at a constant temperature for 2 hours. The heating device is turned off, and nitrogen gas is kept introduced until the furnace cools naturally to room temperature to obtain the primary thermal catalytic product.

[0066] S5. Place the primary product of thermal catalysis into a beaker, add deionized water and stir and wash for 10 min. After vacuum filtration, repeat the washing operation until the pH of the filtrate is 7 and neutral. Dry the filter residue in an oven at 105℃ for 8 h, pulverize it and pass it through a 120-mesh sieve to obtain the desulfurized bean stalk-based active porous carbon material (denoted as sample M1). The desulfurized bean stalk-based active porous carbon material is one of the porous carbon adsorbent materials of this invention.

[0067] 2. Application testing of samples in wastewater treatment

[0068] Sample M1 was added to water containing Rhodamine B (i.e., wastewater), and the pH of the water was adjusted to 2-10. The mixture was stirred at 200 r / min at room temperature. The BET specific surface area, total pore volume, and mesopore volume ratio were measured by nitrogen adsorption-desorption method. The maximum adsorption capacity and 60-minute adsorption capacity of Rhodamine B were measured by static adsorption method. The sulfide removal rate was measured by spectrophotometry. The adsorption performance retention rate after 7 adsorption-desorption cycles was measured by ethanol elution and regeneration method. The test results are shown in Table 1.

[0069] Table 1 Test results of various indicators for sample M1

[0070]

[0071] Example 2

[0072] 1. Sample preparation

[0073] Unlike Example 1, this example uses 70g of ferric sulfate modified bean stalk powder and 30g of desulfurization ash, a byproduct of flue gas desulfurization from a coal-fired power plant treated with S1. The remaining steps are the same as in Example 1 to prepare sample M2.

[0074] 2. Application testing of samples in wastewater treatment

[0075] The performance of sample M2 was tested using the same test method as in Example 1, and the results are shown in Table 2.

[0076] Table 2 Test results of various indicators for sample M2

[0077]

[0078] Compared with Example 1, Example 2 had an excessively high proportion of desulfurization ash. Although the sulfide removal rate was slightly improved, the pores were squeezed, and the adsorption performance and cycle stability decreased. This proves that excessive desulfurization ash will sacrifice the material's adsorption performance, and the 8:2 ratio is better.

[0079] Example 3

[0080] 1. Sample preparation

[0081] Unlike Example 1, in this example, 90g of ferric sulfate modified bean stalk powder and 10g of desulfurization ash, a byproduct of flue gas desulfurization from a coal-fired power plant treated with S1, were weighed, and the remaining steps were the same as in Example 1 to obtain sample M3.

[0082] 2. Application testing of samples in wastewater treatment

[0083] The performance of sample M3 was tested using the same test method as in Example 1, and the results are shown in Table 3.

[0084] Table 3 Test results of various indicators for sample M3

[0085]

[0086] Compared to Example 1, Example 3 had an insufficient proportion of desulfurization ash, lacking the synergistic adsorption effect between the active components and porous carbon in the desulfurization ash. Consequently, its adsorption performance was slightly lower than that of Example 1 (the maximum adsorption capacity of Rhodamine B decreased from 481.54 mg / g to 472.3 mg / g, and the 60-minute adsorption capacity decreased from 409.9 mg / g to 398.5 mg / g), confirming that "the adsorption performance was not optimal." The sulfide removal rate decreased to 82%, failing to meet the treatment requirements of sulfur-containing Rhodamine B composite wastewater, and the adsorption performance was also not optimal, further verifying that 8:2 is the optimal raw material ratio. Although the pore structure of Example 3 was slightly better, the amount of desulfurization ash added was only 10 g less than that of Example 1, resulting in a significant shortage of chemically active sites. The decrease in the contribution of chemical adsorption exceeded the increase in physical adsorption, thus leading to a slight decrease in the total adsorption capacity.

[0087] Example 4:

[0088] In another dechlorination application of the porous carbon adsorbent material of the present invention.

[0089] 1. Sample preparation

[0090] Marble waste stone powder was used to replace industrial solid waste desulfurization ash. The other steps were the same as those in Example 1. The prepared adsorbent material was designated as sample M4.

[0091] 2. Application testing of samples in wastewater treatment

[0092] Prepare a simulated water sample with a residual chlorine concentration of 5 mg / L.

[0093] Accurately weigh 0.1g of dechlorination material sample and add it to 100mL of simulated water sample. Place the sample in a constant temperature water bath shaker and conduct an adsorption experiment at 25℃ and 150r / min. Take a sample after 120min of adsorption and filter it through a 0.45μm filter membrane.

[0094] Take 25 mL of the filtered liquid into an Erlenmeyer flask, add 5 mL of sulfuric acid solution for acidification, then add 1 mL of starch indicator, and titrate with 0.01 mol / L sodium thiosulfate standard solution until the blue color fades. Record the volume of sodium thiosulfate standard solution consumed, and calculate the residual chlorine, dechlorination rate, and adsorption capacity. The dechlorination performance results of the dechlorination material samples obtained in the experiment are shown in Table 4.

[0095] Table 4 shows the results of the chlorine removal performance of the comparative samples.

[0096]

[0097] The stability and regeneration performance of the dechlorination material sample M4 prepared by the present invention were tested. The adsorption saturated sample M4 was placed in a muffle furnace and calcined at 300℃ for 2 hours for regeneration treatment. The adsorption-regeneration experiment was repeated 5 times, and the dechlorination rate after each regeneration was measured. The results are shown in Table 5.

[0098] Table 5. Test results of regeneration performance of dechlorination material sample M4

[0099]

[0100] As shown in Table 5, after 5 adsorption-regeneration cycles, the dechlorination rate of the dechlorination material prepared by this invention remains above 94%, indicating that the material has good stability and regeneration performance, can be reused, and reduces the cost of use.

[0101] Comparative Example 1

[0102] 1. Sample preparation (preparation of unmodified soybean straw-based carbon materials)

[0103] S1. Select agricultural waste bean stalks, remove impurities, rinse with deionized water, remove impurities using a drum-type impurity remover, rinse three times with deionized water in a high-pressure spray washing line, dry with a mesh belt dryer at 105±5℃ until the moisture content is ≤3%, and pulverize to a particle size <0.178mm using a two-stage pulverizing system. The material is then screened through an 80-mesh vibrating screen. The material that passes through the screen is bean stalk powder, and the material that passes through the screen is returned to the two-stage pulverizing system for reprocessing.

[0104] S2. Spread the bean stalk powder treated in S1 onto a quartz boat and put it into a self-made thermal catalytic furnace. Nitrogen gas is introduced as a protective gas, and the nitrogen flow rate is controlled at 80 mL / min. The temperature is raised to 750℃ at a rate of 8℃ / min, and the furnace is kept at a constant temperature for 2 hours for thermal catalysis. The heating device is then turned off, and nitrogen gas is kept introduced until the furnace cools down to room temperature naturally to obtain the primary product.

[0105] S3. Place the primary product from S2 into a beaker, add deionized water and stir and wash for 10 min. After vacuum filtration, repeat the washing operation until the pH of the filtrate is 7 and neutral. Dry the filter residue in an oven at 105℃ for 8 h, pulverize it and pass it through a 120-mesh sieve to obtain unmodified soybean straw-based carbon material, which is denoted as sample D1.

[0106] 2. Application testing of samples in wastewater treatment

[0107] The same test method as in Example 1 was used to test the performance of sample D1 and compared with that in Example 1. The results are shown in Table 6.

[0108] Table 6. Performance comparison results of Sample M1 from Example 1 and Sample D1 from Comparative Example 1

[0109]

[0110] Comparative Example 2

[0111] 1. Sample preparation (unmodified soybean stalk-desulfurized ash composite carbon material) (ratio 8:2, without ferric sulfate modification)

[0112] Unlike Example 1, this example does not include the S2 ferric sulfate modification step in Example 1. The remaining steps are the same as in Example 1 (it should be noted that since S2 is not included in this example, the bean stalk powder in S1 is directly weighed in S3) to obtain unmodified bean stalk-desulfurized ash composite carbon material (denoted as sample D2).

[0113] 2. Application testing of samples in wastewater treatment

[0114] The same test method as in Example 1 was used to test the performance of sample D2 and compared with that in Example 1. The results are shown in Table 7.

[0115] Table 7. Performance comparison results of Sample M1 from Example 1 and Sample D2 from Comparative Example 2

[0116]

[0117] Compared with Comparative Example 2, after modification with ferric sulfate, the pore structure parameters, Rhodamine B adsorption performance and cycle stability of the material in Example 1 were significantly improved, while the desulfurization performance remained basically the same. This proves that ferric sulfate modification is the key to improving the core adsorption performance and structural stability of the material, and the desulfurization function is mainly provided by the desulfurization ash.

[0118] Comparative Example 3

[0119] 1. Sample preparation (ferric sulfate modified soybean straw carbon material)

[0120] Unlike Example 1, this example does not include the desulfurization ash treatment step of flue gas desulfurization byproducts in Example 1 (S1). Therefore, in this example, 100g of ferric sulfate modified bean stalk powder is selected as the single raw material in S3, and the remaining steps are the same as in Example 1. Ferric sulfate modified bean stalk carbon material (denoted as sample D3) is obtained.

[0121] 2. Application testing of samples in wastewater treatment

[0122] The D3 performance of the sample was tested using the same test method as in Example 1 and compared with that of Example 1. The results are shown in Table 8.

[0123] Table 8. Performance comparison results of Sample M1 in Example 1 and Sample D3 in Comparative Example 3

[0124]

[0125] Compared with Example 1, Comparative Example 3 had no desulfurization ash added, the material had almost no desulfurization function, and the cycle stability was slightly lower. This proves that the appropriate addition of desulfurization ash is the key to realizing the desulfurization function of the material and improving the cycle stability, and it forms a synergistic effect with the modification of ferric sulfate.

[0126] Comparative Example 4

[0127] 1. Sample preparation (traditional commercial adsorbent materials)

[0128] Select the national standard activated carbon brand Tanerno wood-based activated carbon (industrial grade), and crush it through an 80-mesh sieve (referred to as sample D4).

[0129] 2. Application testing of samples in wastewater treatment

[0130] The same test method as in Example 1 was used to test the performance of sample D4 and compared with that in Example 1. The results are shown in Table 9.

[0131] Table 9. Performance comparison results of Sample M1 in Example 1 and Sample D4 in Comparative Example 4

[0132]

[0133] The material in Example 1 of this invention far surpasses commercially available wood-based activated carbon in terms of pore structure, adsorption performance, desulfurization performance, and cycle stability. Moreover, it uses agricultural and industrial solid waste as raw materials, which reduces the preparation cost and solves the defects of traditional adsorption materials such as high cost, single function, and poor cycle performance, thus possessing advantages for large-scale application.

[0134] In summary, based on Example 1 and Comparative Examples 1-3, the following conclusions can be drawn:

[0135] 1. Hole Structure Synergy: Balancing Hole Formation and Load

[0136] Comparative Example 3 (Modification Only): BET specific surface area was 302.7 m² / g, with a mesoporous content of 61%, indicating that ferric sulfate modification effectively constructed a multi-level pore structure. Comparative Example 2 (Unmodified + Desulfurization Ash): BET specific surface area was 215.3 m² / g, with a mesoporous content of 48%, indicating that adding desulfurization ash alone improved the pore structure to some extent, but the effect was limited. Example 1 (Modified + Desulfurization Ash): BET specific surface area increased to 388.1 m² / g, with a mesoporous content as high as 72%, significantly higher than the effects of the two single components.

[0137] Synergistic mechanism: The pores formed by ferric sulfate modification provide a uniform loading space for desulfurization ash, avoiding the agglomeration and blockage of the pores; at the same time, the presence of desulfurization ash promotes the iron-based catalytic pore-forming process, forming more mesoporous structures, optimizing the pore distribution, and providing more active sites for adsorption.

[0138] 2. Synergistic Adsorption Performance: Dual Enhancement of Adsorption Capacity and Rate

[0139] Comparative Example 3 (modified only): Maximum adsorption capacity 395.4 mg / g, 60-minute adsorption capacity 312.5 mg / g, demonstrating the core enhancing effect of modification on adsorption performance. Comparative Example 2 (unmodified + desulfurization ash): Maximum adsorption capacity 268.73 mg / g, 60-minute adsorption capacity 165.7 mg / g, indicating that desulfurization ash itself contributes to dye adsorption, but far less than the effect of modification. Example 1 (modified + desulfurization ash): Maximum adsorption capacity 481.54 mg / g, 60-minute adsorption capacity 409.9 mg / g, not only far exceeding Comparative Example 3, but also far exceeding the simple additive effect of the two.

[0140] Synergistic mechanism: The high specific surface area and mesoporous structure of the modified material provide sufficient adsorption sites for Rhodamine B; the calcium-based components in the desulfurization ash have additional interactions with the dye molecules (such as electrostatic adsorption and complexation), which further enhances the adsorption capacity and rate, achieving a dual enhancement of "pore adsorption + chemical action".

[0141] 3. Synergistic Cyclic Stability: Long-Term Maintenance of Structure and Performance

[0142] Comparative Example 3 (Modified Only): After 7 cycles, the performance retention rate was 79%, indicating that the modification enhanced the stability of the carbon skeleton. Comparative Example 2 (Unmodified + Desulfurization Ash): After 7 cycles, the performance retention rate was 68%, indicating that the addition of desulfurization ash improved the cycle stability to some extent, but the effect was limited.

[0143] Example 1 (Modified + Desulfurization Ash): After 7 cycles, the performance retention rate reached 88%, which is significantly better than all single components.

[0144] Synergistic mechanism: The stable carbon skeleton formed by ferric sulfate modification provides the structural basis for the material; the calcium-based components of desulfurization ash form a stable load in the pores, further enhancing the structural stability of the material, reducing the loss of active sites and pore collapse during multiple adsorption-desorption processes, thereby improving the recycling performance.

[0145] Therefore, based on the above analysis, we can conclude that:

[0146] 1. The optimal weight ratio of ferric sulfate modified soybean straw powder to desulfurization ash is 8:2. Under this ratio, the material can balance the adsorption performance of Rhodamine B and the removal performance of sulfides, and has excellent cycle stability.

[0147] 2. The synergistic effect of ferric sulfate modification and desulfurization ash addition: the modification constructs multi-level pores to improve adsorption and circulation performance, while the desulfurization ash imparts desulfurization function and realizes solid waste resource utilization.

[0148] 3. Compared with unmodified composite carbon materials, single modified bean stalk carbon materials, and commercially available wood-based activated carbon, the materials prepared by this invention have superior overall performance, lower cost, and more comprehensive functions. They are suitable for the treatment of complex sulfur-containing wastewater containing Rhodamine B and meet the technical requirements for water pollution control and solid waste resource utilization.

[0149] like Figure 1 As shown, the industrial production process of this invention is as follows, in conjunction with the appendix. Figure 1 The device shown is described below:

[0150] Raw material pretreatment and crushing: Bean stalk raw material is quantitatively transported from bean stalk raw material silo (1) to vertical crusher (2), and crushed to bean stalk powder with a particle size ≤0.25 mm for later use; desulfurized ash is dried and crushed by desulfurized ash drying and crushing device (4) to obtain dried desulfurized ash powder with a particle size ≤0.15 mm for later use.

[0151] Continuous modification with ferric sulfate: Soybean stalk powder is fed into a continuous stirring reaction tank (3) with ferric sulfate solution at a material-to-liquid ratio of 1g:(5~20)mL, and fully contacted with ferric sulfate aqueous solution of preset concentration. The mixture is continuously stirred and reacted at 30~60℃ for 1~6h to complete the liquid-solid phase impregnation modification and obtain ferric sulfate modified soybean stalk slurry.

[0152] Raw material mixing and homogenization: Ferric sulfate modified soybean stalk slurry and dry desulfurization ash powder are fed into a high-speed mixer (5) at a mass ratio of 8:2 and stirred at a high speed of 300 r / min for 15~30 min to ensure that the two are fully mixed and homogeneous, so as to obtain thermal catalytic raw materials.

[0153] Simultaneous co-pyrolysis catalysis: The thermal catalytic raw material is loaded into a quartz boat and sent into a quartz boat + carbon-based solid waste thermal catalytic furnace (6). Under nitrogen protection (flow rate 50~100 mL / min), the temperature is programmed to rise to 650~800℃ at a heating rate of 5~10℃ / min, and co-pyrolyzed at a constant temperature for 1~3h. During the pyrolysis process, the synergistic coupling of iron-based catalytic pore formation and calcium-based loading is realized simultaneously. After the pyrolysis is completed, nitrogen is continuously introduced and the material is naturally cooled to room temperature to obtain the primary pyrolysis product.

[0154] Post-processing and molding: The primary pyrolysis product is sent into a vacuum filtration oven (7), washed multiple times with deionized water until the filtrate is neutral, vacuum filtered, dried at 105°C to constant weight, and then pulverized to obtain a loaded desulfurized active porous carbon material.

[0155] like Figure 2(d) shows that the morphology of the porous carbon adsorbent material (desulfurization ash) of the present invention undergoes a fundamental change: the biochar skeleton is completely encapsulated by a large number of spherical minerals (approximately 1-3 μm in diameter), making it almost impossible to distinguish the original carbon structure. This clustering phenomenon originates from the synergistic effect of Ca²⁺ and Fe³⁺ in the desulfurization ash: Ca²⁺ forms a composite oxide with Fe³⁺ through electrostatic attraction, which crosslinks with the biochar during pyrolysis to form a stable mineral-carbon composite.

[0156] Figure 3 The figures show the fitted curves of the pseudo-first-order and pseudo-second-order kinetic equations for the adsorption of Rhodamine B by four carbon materials (desulfurization ash). As can be seen from the figures, the adsorption capacity of Rhodamine B by all four carbon materials increases with increasing adsorption time. The adsorption processes of soybean straw biochar (a) and ferric sulfate-modified active porous carbon (b) are similar: in the rapid adsorption stage (0-60 min), the adsorption capacity gradually increases, indicating the presence of active sites on the material surface for Rhodamine B adsorption; in the slow adsorption stage (60-120 min), the surface adsorption sites tend to saturate, the site competition effect intensifies, leading to a significant decrease in the adsorption rate; adsorption equilibrium is reached after 120 min. In contrast, the active porous carbon loaded with desulfurization ash (c) and the active porous carbon material loaded with desulfurization ash modified with ferric sulfate (d) also experienced rapid adsorption (0-60 min), but their adsorption capacity was much higher than that of soybean straw biochar (a) and ferric sulfate modified active porous carbon (b). They then entered a slow adsorption stage (60-240 min) and basically reached adsorption equilibrium after 240 min, with equilibrium adsorption capacities of 351 mg / g and 361.6 mg / g, respectively.

[0157] Comparative Example 5:

[0158] 1. Sample preparation

[0159] Marble waste stone powder was used to replace the desulfurization ash in Comparative Example 2, and the remaining steps were the same as in Comparative Example 2. This sample was denoted as D5.

[0160] 2. Application testing of samples in wastewater treatment

[0161] The D5 performance of the sample was tested using the same test method as in Example 4.

[0162] Comparative Example 6:

[0163] 1. Sample preparation

[0164] Marble waste stone powder was used to replace the desulfurization ash in Comparative Example 3, and the remaining steps were the same as in Comparative Example 3. This sample was denoted as D6.

[0165] 2. Application testing of samples in wastewater treatment

[0166] The performance of sample D6 was tested using the same test method as in Example 4.

[0167] Comparative Example 7:

[0168] 1. Sample preparation

[0169] Sample D4 from Comparative Example 4 was used.

[0170] 2. Application testing of samples in wastewater treatment

[0171] The performance of sample D4 was tested using the same test method as in Example 4.

[0172] The dechlorination performance results of Examples 4 and Comparative Examples 5-7 are shown in Table 10.

[0173] Table 10 shows the chlorine removal performance results of the comparative samples (adsorption time 120 min).

[0174]

[0175] The dechlorination rate and adsorption capacity of the dechlorination material sample M4 prepared by this invention are significantly higher than those of the comparative samples D5, D6, and D4. Among them, the material prepared from unmodified bean stalks has poor dechlorination performance due to insufficient active sites; the material without added marble waste powder has limited dechlorination effect due to insufficiently developed pore structure; and the dechlorination performance of commercially available ordinary activated carbon is also lower than that of the sample of this invention. This proves that the present invention effectively improves the dechlorination performance of the material through the synergistic effect of ferric sulfate modification and marble waste powder.

[0176] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a porous carbon adsorbent material, characterized in that, Includes the following steps: S1. Raw material pretreatment: Carbon-containing biomass solid waste and calcium-containing industrial solid waste are pretreated to obtain pretreated biomass material and pretreated calcium-containing solid waste. S2, Iron-based modification: The pretreated biomass is immersed in an iron-based modifier system for modification to obtain iron-based modified biomass. S3. Raw material mixing: The iron-based modified biomass material is mixed evenly with the pretreated calcium-containing solid waste to obtain a catalytic precursor; S4. Co-pyrolysis: The catalytic precursor is subjected to programmed temperature co-pyrolysis treatment. During the co-pyrolysis process, the synergistic coupling of iron-based catalytic pore formation and calcium-based loading is realized simultaneously. After cooling, the primary pyrolysis product is obtained. S5. Post-processing: The primary pyrolysis product is sequentially washed with water, separated from solids and liquids, dried and pulverized to obtain the porous carbon adsorbent material.

2. The preparation method according to claim 1, characterized in that, The raw material pretreatment in S1 includes impurity removal, washing, drying, and crushing; the carbon-containing biomass solid waste is agricultural biomass solid waste, and the calcium-containing industrial solid waste is at least one of calcium sulfate solid waste and calcium carbonate solid waste.

3. The preparation method according to claim 1, characterized in that, The iron-based modification in S2 is a liquid-solid phase impregnation and stirring modification, and the modification process includes a continuous process of impregnation, stirring reaction, solid-liquid separation, washing, and drying.

4. The preparation method according to claim 1, characterized in that, The specific steps for mixing raw materials in S3 are as follows: weigh iron-based modified biomass and pretreated calcium-containing solid waste at a mass ratio of 7~9:1~3, put them into a high-speed mixer and stir to obtain a uniformly mixed thermocatalytic raw material.

5. The preparation method according to claim 1, characterized in that, The co-pyrolysis cooling process in S4 is carried out in an atmosphere where protective gas is continuously introduced; during the formation of iron-based channels, the calcium-based components are simultaneously loaded in situ onto the surface and within the channels of the porous carbon skeleton.

6. The preparation method according to claim 3, characterized in that, The system of the iron-based modifier in S2 is an aqueous solution of ferric sulfate; the impregnation material-to-liquid ratio is the mass-to-volume ratio of the pretreated biomass material to the aqueous solution of ferric sulfate 1g:(5~20)mL, and the stirring reaction time is 2~6h.

7. The preparation method according to claim 2, characterized in that, The calcium sulfate-containing solid waste is desulfurization ash, and the calcium carbonate-containing solid waste is marble waste powder.

8. The preparation method according to claim 5, characterized in that, The heating rate of the programmed heating co-pyrolysis in S4 is 5~10℃ / min, the final co-pyrolysis temperature is 650~800℃, and the isothermal co-pyrolysis time is 1~3h; the cooling is natural cooling to room temperature.

9. A porous carbon adsorbent material, characterized in that, The material is prepared by the preparation method according to any one of claims 1 to 8; the material has a hierarchical porous structure formed by iron-based catalysis, and calcium-based components are loaded in situ on the surface of the pores and on the framework.

10. An application of a porous carbon adsorbent material in wastewater treatment, characterized in that, Adding the porous carbon adsorbent material as described in claim 9 to the water body to be treated enables the simultaneous removal of dye pollutants and sulfides or chlorides from the water body.

Images