Preparation method and application of magnetic modified plant source alginate biochar adsorption material
By preparing magnetically modified plant-derived alginate biochar adsorbent materials, the environmental protection and stability issues of existing technologies for treating systems where heavy metal ions and organic dyes coexist have been resolved, achieving efficient and renewable treatment of composite pollutants.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-18
- Publication Date
- 2026-03-13
AI Technical Summary
Existing adsorption materials suffer from poor environmental performance, unstable magnetic components, high cost, unstable structure, and limited functionality when treating systems where heavy metal ions and organic dyes coexist, making them difficult to adapt to complex aquatic environments.
Magnetic modified alginate biochar was prepared using various plant-derived biomass wastes. Stable gel sphere structures were formed by crosslinking agents such as citric acid and microwave-assisted dispersion technology. β-cyclodextrin and magnetic oxides were loaded onto these spheres to construct a porous network, enabling the synergistic adsorption of heavy metal ions and organic dyes.
It achieves efficient synergistic adsorption of heavy metal ions and organic dyes. The material exhibits good stability in complex aquatic environments, high magnetic separation efficiency, and rapid regeneration. It is suitable for complex wastewater treatment and has good sustainability and engineering application potential.
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Figure CN121648876A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of water pollution treatment technology, specifically relating to a method for preparing and applying a magnetically modified plant-derived alginate biochar adsorbent material. Background Technology
[0002] With the acceleration of industrialization, pollutants such as lead (Pb(II)) and methylene blue (MB) emitted from industries such as mineral processing, dyeing and finishing, and electroplating pose a serious threat to aquatic ecosystems and human health. Pb(II), as a typical heavy metal ion, has bioaccumulation and neurotoxicity, while MB is a common organic cationic dye with high stability and visibility in wastewater. When the two coexist, they form a complex compound pollution system, significantly increasing the difficulty of treatment.
[0003] Currently, commonly used water remediation technologies include chemical precipitation, membrane separation, ion exchange, biological treatment, and adsorption. Among these, adsorption is widely used due to its simplicity, low cost, and low risk of secondary pollution. Regarding adsorption materials, biochar exhibits excellent adsorption performance due to its well-developed pore structure and abundant surface functional groups. To further improve the selectivity and recyclability of adsorption materials, researchers commonly employ strategies such as introducing magnetic components and surface functionalization modification.
[0004] In existing technologies, some solutions utilize β-cyclodextrin (β-CD) to modify magnetic biochar or polymeric carriers, and use organic crosslinking agents such as ethylenediaminetetraacetic acid (EDTA) or polyamine compounds to achieve synergistic adsorption of heavy metals and organic dyes. However, these systems generally suffer from the following shortcomings: First, the crosslinking agents are not environmentally friendly. Although ligands such as EDTA can enhance complexation ability, they are difficult to degrade and pose potential environmental risks. Second, the magnetic components are singular and prone to aggregation. Most use Fe3O4 as the magnetic core, lacking dispersion and stability, and are prone to demagnetization or aggregation under high ionic strength or acidic conditions. Third, the raw material costs and renewability are insufficient. Chemical substrates such as cyclodextrin polymers, carbon nanofibers, or modified resins are often used, resulting in complex preparation processes, high costs, and weak environmental friendliness. Fourth, the structural and cycling stability is poor. Some chitosan or resin-based materials have limited mechanical strength after crosslinking, and their performance degrades significantly after multiple adsorption-desorption cycles. Fifth, the adsorption system has a single function, mostly targeting single pollutants, and lacks adaptability and application verification for actual complex wastewater (such as the coexistence of metal ions and organic dyes in mineral processing wastewater).
[0005] Therefore, there is an urgent need to develop an environmentally friendly adsorption system that uses multi-source plant biomass as carbon-based material and employs green cross-linking agents and composite magnetic materials to achieve efficient removal, recyclability, and rapid separation of complex pollution from heavy metal ions and organic dyes. Summary of the Invention
[0006] To address at least one technical problem in the existing technology, this application provides a method for preparing magnetically modified plant-derived alginate biochar adsorbent material, characterized by the following steps: S1. Plant-derived biochar is obtained by drying, pulverizing, and sieving plant-derived biomass waste, followed by pyrolysis, and then mixed with magnetic material, β-cyclodextrin, and an organic acid crosslinking agent to form a composite slurry; wherein the magnetic material is Fe3O4 nanoparticles, magnetic manganese oxide, magnetic nickel-iron oxide, or magnetic cobalt-iron oxide; and the organic acid crosslinking agent is citric acid; S2. The composite slurry is dispersed and added to sodium alginate solution and stirred evenly. At room temperature, it is then added dropwise to calcium chloride solution to crosslink and form gel spheres. S3. After washing and freeze-drying the gel spheres, magnetically modified plant-derived alginate biochar adsorbent material is obtained.
[0007] In the above method, in S1, the plant-derived biomass waste is a mixture of corn stalks, sugarcane bagasse, rice straw, and urban greening pruning waste in a mass ratio of 1:1:1:1; preferably, rice straw and sugarcane bagasse are mixed in a mass ratio of 1:1; the drying, crushing, and sieving are performed by drying in an oven at 80°C for 24 hours, crushing, and sieving through a 100-mesh sieve; the pyrolysis is carried out under oxygen-limited conditions, with a pyrolysis temperature of 250–400°C and a time of 1–4 hours; preferably, the pyrolysis temperature is 300°C and the time is 2 hours.
[0008] In the above method, in S1, the magnetic material is MnFe2O3, NiFe2O4 or CoFe2O4; preferably NiFe2O4; the mass ratio of the magnetic material, biochar and β-cyclodextrin is (0.5–1.5):1:(0.5–1.5); preferably 1:1:1.
[0009] In the above method, S1 further includes: adding a dispersing agent to make the mixture uniformly dispersed and combined; the dispersing agent is sodium dihydrogen phosphate and polyethylene glycol, and the mass ratio of the two is 1:2.5.
[0010] In the above method, in S1, the organic acid crosslinking agent further includes: malic acid, tartaric acid, sodium citrate or sodium malate; the amount of citric acid, malic acid, tartaric acid, sodium citrate or sodium malate added is 1 to 5% of the total mass of the mixture, preferably 3%.
[0011] In the above method, in S2, the dispersion treatment is a microwave-assisted dispersion treatment with a power of 100–200W, a processing temperature of 30–60℃, and a processing time of 30–90min; preferably, the power is 136W, the processing temperature is 40℃, and the processing time is 60min.
[0012] In the above method, in S2, the solid-liquid ratio of sodium alginate to composite slurry is (20–30) g:1 L, the concentration of calcium chloride solution is 20 g / L, and the crosslinking time is 8–24 h; preferably, the crosslinking time is 12 h.
[0013] In another aspect, this application provides a method for synergistic treatment of a pollution system containing both heavy metals and organic dyes using a magnetically modified plant-derived alginate biochar adsorbent prepared by the above method. The method is characterized by adding the adsorbent to the pollution system at a solid-liquid ratio of (0.1–2.0) g:1 L, with an adsorption time of 30–180 min; preferably, a solid-liquid ratio of 0.5 g:1 L and an adsorption time of 120 min; the pollution system is saline wastewater composed of Pb(II), Cu(II), Zn(II), and / or methylene blue, with a pH of 3–9.
[0014] In the above treatment method, after adsorption is completed, the separated adsorbent material is placed in a mixed solution prepared by 0.1 mol / L citric acid aqueous solution and methanol at a volume ratio of 1:1 for 1 h, and then washed with deionized water until the washing solution is neutral before freeze-drying the material to complete the regeneration.
[0015] In the above treatment method, the polluted system is repeatedly sampled 4-5 times until the emission standards are met.
[0016] This application has at least the following beneficial technical effects: This invention addresses the shortcomings of existing adsorbent materials in terms of environmental friendliness, structural stability, and versatility by proposing a method for preparing magnetically modified plant-derived alginate biochar adsorbent materials and its application. By introducing various plant-derived solid wastes (such as corn stalks, sugarcane bagasse, rice straw, and urban greening pruning waste) to prepare biochar, high-value utilization of agricultural and urban waste is achieved. The raw materials are widely available and inexpensive, aligning with the concepts of resource recycling and green development.
[0017] This invention uses organic weak acids such as citric acid, malic acid and their sodium salts as crosslinking agents to replace the traditional refractory ethylenediaminetetraacetic acid (EDTA), thus avoiding environmental residues and biodegradability issues. It also uses sodium dihydrogen phosphate and polyethylene glycol to construct a stable dispersion system, enabling β-cyclodextrin and magnetic particles to be uniformly combined on the surface of biochar.
[0018] The magnetic functional components are selected from ferrite composites such as Fe3O4, NiFe2O4, CoFe2O4, or MnFe2O4. Microwave-assisted dispersion allows for rapid heating and promotes uniform dispersion of particles in the slurry, enabling more stable loading of the magnetic oxides onto the composite interface of biochar and β-cyclodextrin. This loading method not only inhibits the aggregation of magnetic particles but also enhances the structural stability and magnetic response intensity of the composite material in complex aquatic environments such as acidity and high salinity, thereby significantly improving the magnetic separation efficiency and recycling performance of the adsorbed material. The resulting composite material, after the introduction of sodium alginate, undergoes Ca2+ reaction upon dropwise addition to a CaCl2 solution. 2+ - The "egg-box" ionic cross-linking structure of alginate forms uniform and dense gel spheres. The three-dimensional porous network of the gel spheres can firmly encapsulate and fix biochar and magnetic components, ensuring a stable distribution of functional components within the spheres while providing abundant mass transfer channels and adsorption sites. This ionic cross-linking structure endows the spheres with high mechanical strength, water resistance, and deformation recovery, allowing the material to maintain its integrity during repeated adsorption-desorption cycles, preventing breakage or loss, thus ensuring its long-term reusability and engineering application performance.
[0019] The material of this invention exhibits significant synergistic adsorption capacity for Pb(II), Cu(II), Zn(II), and the organic dye methylene blue in a simulated mineral processing wastewater system. It can achieve rapid adsorption, magnetic separation recovery, and efficient desorption regeneration, maintaining a removal rate of over 80% even after being reused four times. Overall, this invention achieves the goal of green, efficient, and renewable synergistic treatment of multiple pollutants, demonstrating good sustainability and engineering application potential. Attached Figure Description
[0020] Figure 1 Comparison of SEM morphology of plant-derived biochar and its modified adsorbent materials before and after adsorption. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0022] The following is in conjunction with the appendix Figure 1 This application provides a more detailed description of the preparation method and application of the magnetically modified plant-derived alginate biochar adsorbent material.
[0023] Example 1 To investigate the effects of different plant-derived raw materials on the performance of the adsorbent, one or more of the following were selected as biochar precursors: corn stalks, sugarcane bagasse, rice straw, and urban greening pruning waste (mixed in mass ratios of 1:1, 1:1:1, or 1:1:1:1 by mass). The raw materials were washed and dried in an oven at 80 ℃ for 24 h, then pulverized and passed through a 100-mesh sieve. Subsequently, they were pyrolyzed at 250–400 ℃ for 1–4 h under limited oxygen conditions to obtain plant-derived biochar, which was then cooled to room temperature for later use.
[0024] Biochar, Fe3O4 nanoparticles, and β-cyclodextrin were weighed at a mass ratio of (0.5–1.5):1:(0.5–1.5). Citric acid (1–5% by mass) was added as a crosslinking agent, and 0.2% sodium dihydrogen phosphate and 0.5% polyethylene glycol were added to form a stable dispersion system. An appropriate amount of deionized water was added and mixed thoroughly to obtain a reaction slurry. This slurry was placed in a microwave reactor and reacted at 30–60℃ and 100–200W for 30–90 min to obtain a uniformly dispersed magnetically modified biochar composite slurry.
[0025] The microwave-treated slurry was mixed with sodium alginate solution at a solid-liquid ratio of (20–30 g): 1 L. After thorough mixing, the mixture was slowly added dropwise to a 20 g / L CaCl2 crosslinking solution using a syringe pump. Crosslinking was carried out at room temperature for 8–24 h to form gel spheres. After crosslinking, the gel spheres were removed, repeatedly washed with deionized water to remove residual ions from the surface, and then freeze-dried for 24 h to obtain the target adsorbent material.
[0026] In this embodiment, plant-derived biochar was prepared by pyrolysis at 300 °C for 2 h, with a mass ratio of biochar, Fe3O4 nanoparticles, and β-cyclodextrin of 1:1:1; microwave-assisted dispersion was performed at a power of 136 W, a temperature of 40 °C, and a time of 60 min; the mass fraction of citric acid was 2%; the slurry and sodium alginate solution were mixed at a solid-liquid ratio of 20 g:1 L, and the crosslinking reaction time was 12 h.
[0027] Adsorption performance tests were conducted at 25 °C. Initial concentrations of 300 mg / L Pb(II) and 200 mg / L methylene blue (MB) solutions were prepared, and the pH of the system was adjusted to 5.0. 0.01 g of the obtained dried adsorbent material was weighed and added to 20 mL of the simulated wastewater. The mixture was shaken and adsorbed in a constant-temperature shaker for 120 min, then filtered. The supernatant was collected, and the remaining concentrations of Pb(II) and MB were determined. The removal rate and unit adsorption capacity were calculated.
[0028] Table 1 Comparison of the removal effects of different plant source combinations on Pb(II) and MB
[0029] As shown in Table 1, the experimental results show that the prepared adsorbent material exhibits good adsorption performance under different plant-derived raw material systems, with removal rates of Pb(II) and MB both exceeding 85%, verifying the applicability of various agricultural and garden wastes as biochar raw materials.
[0030] Among them, the material prepared from rice straw performed best in the single raw material system, with removal rates of 92.4% and 91.8% for Pb(II) and MB, respectively.
[0031] In the multi-component system, the material prepared by mixing rice straw and sugarcane bagasse in a 1:1 mass ratio showed the best performance, with removal rates of Pb(II) and MB as high as 96.4% and 96.0%, respectively.
[0032] The results showed that solid wastes from different plant sources could be used to construct high-performance adsorption materials, while the rice straw-sugarcane bagasse composite system exhibited superior synergistic adsorption characteristics in terms of pore structure, functional group distribution, and surface polarity. This is because the microporous structure and high density of oxygen-containing functional groups formed after the pyrolysis of rice straw provide sufficient complexation sites for heavy metals, while the biochar obtained from the pyrolysis of sugarcane bagasse has a higher proportion of mesopores and a more stable carbon skeleton, providing effective mass transfer channels for the diffusion and entry of organic dye molecules. When the two are combined in a 1:1 ratio, their microporous-mesoporous structures are complementary, the types of active functional groups are more abundant, and the surface polarity and hydrophilicity are more balanced, which is conducive to simultaneously enhancing the complexation adsorption of metal ions such as Pb(II) and the electrostatic / π–π interaction of MB, thereby obtaining the optimal synergistic adsorption performance.
[0033] Example 2 To investigate the influence of magnetic components on the performance of adsorbent materials, based on the plant-derived raw materials being a 1:1 mass mixture of rice straw and sugarcane bagasse, different types of magnetic materials were used to prepare adsorbent materials, and their adsorption performance was compared and evaluated.
[0034] Magnetic materials include Fe3O4 nanoparticles, magnetic manganese oxide (MnFe2O3), magnetic nickel-iron oxide (NiFe2O4), and magnetic cobalt-iron oxide (CoFe2O4).
[0035] Rice straw and sugarcane bagasse were washed, dried, and pulverized, then mixed and pyrolyzed at 300 °C under limited oxygen conditions for 2 h to obtain biochar. Magnetic materials, biochar, and β-cyclodextrin were mixed at a mass ratio of 1:1:1, with 2% citric acid added as a crosslinking agent, and 0.2% sodium dihydrogen phosphate and 0.5% polyethylene glycol added to form a stable dispersion system. The resulting slurry was microwave-treated at 40 °C and 136 W for 60 min, then mixed evenly with a 20 g / L sodium alginate solution, and crosslinked by dropwise addition to a 20 g / L CaCl2 solution for 12 h to form gel spheres. After crosslinking, the gel spheres were removed, washed with deionized water to remove residual ions, and then freeze-dried for 24 h to obtain the target adsorbent material.
[0036] At 25 °C, 0.01 g of dry adsorbent material was weighed and added to 20 mL of Pb(II) solution with an initial concentration of 300 mg / L and methylene blue (MB) solution with an initial concentration of 200 mg / L. The pH of the system was adjusted to 5.0. After adsorption for 120 min, the supernatant was filtered and the remaining concentrations of Pb(II) and MB were determined.
[0037] Table 2 Comparison of removal rates of Pb(II) and MB by different magnetic materials
[0038] As shown in Table 2, different magnetic materials can impart good magnetic responsiveness and adsorption performance to the adsorbent materials. Compared with traditional Fe3O4 materials, doped magnetic oxides have a significant effect on improving adsorption performance. Among them, the adsorbent material prepared with NiFe2O4 as the magnetic modification component performs the best, with removal rates of 98.1% and 97.8% for Pb(II) and MB, respectively.
[0039] The results show that NiFe2O4 possesses higher structural stability and specific surface area, which enhances the synergistic effect between surface active sites and pollutants, thereby significantly improving the adsorption performance of the composite material. This is because NiFe2O4 has a spinel structure, stable lattice, good particle dispersion, and is not prone to agglomeration. The Fe–O and Ni–O groups on its surface can provide more metal active centers that can complex with Pb(II). Simultaneously, its high specific surface area and oxygen-containing functional groups enhance the electrostatic adsorption and complexation of the cationic dye MB, promoting the simultaneous removal of heavy metals and dyes. The combined effect of these factors results in the NiFe2O4-containing composite adsorbent exhibiting higher synergistic adsorption efficiency.
[0040] Example 3 To evaluate the effect of the type of organic acid crosslinking agent on the performance of the adsorbent material, based on the optimal plant source combination (rice straw and sugarcane bagasse in a 1:1 mass ratio) and magnetic material (NiFe2O4) determined in Example 2, three typical weak organic acids, namely citric acid, malic acid and tartaric acid, were selected as crosslinking agents. While keeping other experimental conditions consistent, adsorbent materials under different crosslinking systems were prepared, and their adsorption performance for Pb(II) and MB was compared.
[0041] The specific steps are as follows: Pre-prepared rice straw-sugarcane bagasse biochar was mixed with NiFe2O4 nanoparticles and β-cyclodextrin at a mass ratio of 1:1:1. Citric acid, malic acid, or tartaric acid (2% by mass) were added as crosslinking agents, along with 0.2% sodium dihydrogen phosphate and 0.5% polyethylene glycol to form a stable dispersion system. Each slurry was placed in a microwave reactor and treated at 40 °C and 136 W for 60 min. Then, it was mixed into a 20 g / L sodium alginate solution, stirred evenly, and then added dropwise to a 20 g / L CaCl2 solution. Crosslinking was carried out at room temperature for 12 h to form gel spheres. Finally, the target adsorbent material was obtained by freeze-drying for 24 h.
[0042] Adsorption performance tests were conducted at 25 ℃ and pH 5. 0.01 g of adsorbent material was weighed and added to 20 mL of either a 300 mg / L Pb(II) solution or a 200 mg / L methylene blue (MB) solution. After shaking and adsorption for 120 min, the supernatant was collected to determine the residual pollutant concentration, and the removal rate and adsorption capacity were calculated.
[0043] Table 3 Comparison of the removal effects of different organic acid crosslinking agents on Pb(II) and MB.
[0044] As can be seen from the results in Table 3, all three organic acid crosslinking systems can effectively remove Pb(II) and MB, indicating that the selected weak organic acids all have certain crosslinking effects and enhanced adsorption performance.
[0045] However, the adsorbent material prepared using citric acid as a crosslinking agent exhibited the best adsorption performance, with removal rates of 97.2% and 96.9% for Pb(II) and MB, respectively, which were significantly higher than those of the malic acid group and the tartaric acid group.
[0046] The results show that citric acid, with its tricarboxylic acid structure, can simultaneously provide multiple carboxyl and hydroxyl groups as reaction sites. Under microwave-assisted conditions, it can form a stable multi-site crosslinking network with β-cyclodextrin and hydroxyl groups on the surface of biochar, significantly improving the crosslinking density and structural compactness of the composite material. Simultaneously, the multi-carboxyl group characteristic of citric acid endows it with strong metal ion chelating ability, forming richer and more active metal coordination centers on the material surface, thereby enhancing the complexation and adsorption of metal ions such as Pb(II) and Cu(II). Furthermore, the multi-carboxyl and hydroxyl groups introduced by citric acid can also improve the hydrophilicity and interfacial stability of the composite material, promoting the mass transfer and diffusion of organic dyes such as MB and their multi-site interactions, resulting in superior synergistic adsorption efficiency in heavy metal-dye coexistence systems. Based on these multiple mechanisms, the adsorption material prepared using citric acid as a crosslinking agent exhibits significantly better overall performance than malic acid and tartaric acid, making it the most preferred green and environmentally friendly crosslinking agent in this invention. In addition, sodium citrate or sodium malate can also be used as alternative crosslinking agents.
[0047] Example 4 To clarify the influence of pyrolysis process parameters on the performance of adsorbent materials, based on the optimal scheme determined in Example 3 (the plant source was selected as rice straw and sugarcane bagasse in a mass ratio of 1:1, the magnetic material was NiFe2O4, and the crosslinking agent was citric acid), the effects of pyrolysis temperature and time on the adsorption performance of the prepared adsorbent materials were systematically investigated.
[0048] The mixed rice straw and sugarcane bagasse were washed, dried, crushed, and sieved, and then subjected to oxygen-limited pyrolysis under different conditions: (1) 250 ℃, 2 h; (2) 300 ℃, 2 h; (3) 350 ℃, 2 h; (4) 400 ℃, 2 h; (5) 300 ℃, 1 h; (6) 300 ℃, 3 h; (7) 300 ℃, 4 h. The biochar obtained after pyrolysis was naturally cooled to room temperature for later use.
[0049] Subsequently, following the method in Example 3, biochar, NiFe2O4 nanoparticles, β-cyclodextrin, and a crosslinking agent were mixed at a mass ratio of 1:1:1, and the adsorbent material was prepared by microwave-assisted crosslinking treatment. The microwave reaction conditions, pelletizing process, and drying method were the same as those described above.
[0050] The adsorption experiment was conducted at 25 °C, with the pH of the system adjusted to 5.0. The initial concentrations of Pb(II) were 300 mg / L and MB were 200 mg / L. 0.01 g of adsorbent material was weighed and added to 20 mL of simulated contamination solution. After shaking and adsorption for 120 min, the residual concentration of the supernatant was measured, and the removal rate was calculated to evaluate the adsorption performance of the material under different pyrolysis conditions.
[0051] Table 4. Removal efficiency of biochar-based adsorbents for Pb(II) and MB under different pyrolysis conditions.
[0052] As shown in Table 4, different pyrolysis conditions have a significant impact on the performance of the final adsorbent material. Among them, the biochar prepared by pyrolysis at 300 °C for 2 h exhibits the best adsorption performance, with removal rates of 97.6% for Pb(II) and 96.9% for MB, which are significantly better than those under other pyrolysis conditions.
[0053] Lower pyrolysis temperatures (e.g., 250 ℃) lead to incomplete carbonization, preventing the complete pyrolysis of cellulose, hemicellulose, and lignin in plant-derived biomass. This results in an insufficient number of active sites and a limited specific surface area on the biochar surface, thus limiting its adsorption capacity. On the other hand, excessively high temperatures or excessively long pyrolysis times (e.g., 400 ℃ or 4 h) cause the thermal removal of oxygen-containing functional groups such as carboxyl and hydroxyl groups on the biochar surface. Furthermore, excessive carbonization can cause the microporous structure to shrink or collapse, leading to a reduction in effective pore volume and thus decreasing its adsorption capacity for heavy metals and dyes.
[0054] Comprehensive analysis shows that 300 °C and 2 h are the preferred pyrolysis process parameters for the preparation of plant-derived biochar in this invention, which can balance structural integrity and surface activity, and provide a stable basis for subsequent magnetic modification and composite molding.
[0055] Example 5 To further evaluate the adaptability of the prepared adsorbent materials in typical heavy metal-organic dye coexistence systems, Pb(II), Cu(II), and Zn(II) were selected to form composite pollution systems with methylene blue (MB), respectively, and adsorption performance tests were conducted. The adsorbent material used was the composite biochar prepared in Example 1 by mixing rice straw and sugarcane bagasse at a 1:1 mass ratio and pyrolyzing at 300 °C for 2 h, with the remaining preparation processes remaining consistent.
[0056] Three composite pollution solutions were prepared at 25 ℃: Pb(II)+MB, Cu(II)+MB, and Zn(II)+MB systems. The initial concentrations of each metal ion were 300 mg / L, the initial concentration of MB was 200 mg / L, and the pH of the system was adjusted to 5.0. 0.01 g of dried adsorbent was weighed and added to 20 mL of the composite solution. After adsorption by shaking in a constant-temperature shaker for 120 min, the solution was filtered. The remaining concentrations of metal ions and MB in the solution were measured, and the removal rate of each component was calculated.
[0057] Table 5. Pollutant removal efficiency in coexistence systems of different metal ions and MB.
[0058] As shown in Table 5, the prepared adsorption material exhibits excellent adsorption performance in various heavy metal-organic dye coexistence systems, with removal rates of over 88% for the three metal ions and MB. This indicates that the material still has high adsorption stability and adaptability in complex and complex pollution environments.
[0059] Among them, the synergistic adsorption effect of the material is most significant in the Pb(II)+MB system, with removal rates of 97.2% and 96.9% for Pb(II) and MB, respectively.
[0060] The results show that the material can simultaneously achieve efficient removal of heavy metal ions and organic dyes, exhibiting excellent simultaneous adsorption performance and significant synergistic removal effect, demonstrating broad applicability and good potential for engineering applications.
[0061] Example 6 To evaluate the regeneration performance of the prepared adsorbent material, the material obtained by mixing rice straw and sugarcane bagasse at a mass ratio of 1:1 and pyrolyzing it at 300 °C for 2 h in Example 1 was selected as a representative material and multiple adsorption-desorption cycle tests were conducted in the Pb(II)–MB composite pollution system.
[0062] The adsorption experimental conditions were as follows: initial concentration of Pb(II) 300 mg / L, initial concentration of MB 200 mg / L, pH adjusted to 5.0, adsorption temperature 25 ℃, adsorption time 120 min, and adsorbent dosage 0.01 g / 20 mL.
[0063] After adsorption, the adsorbed material was magnetically separated and added to 20 mL of desorption buffer (0.1 mol / L citric acid-methanol mixture, volume ratio 1:1). Desorption was carried out at room temperature with shaking for 1 h. After desorption, the material was thoroughly washed with deionized water until neutral, then freeze-dried again for the next adsorption cycle. The above adsorption-desorption steps were repeated 5 times to evaluate the material's recyclability.
[0064] Table 6 Adsorption performance of adsorbent materials during recycling
[0065] As shown in Table 6, the adsorbent material maintained high adsorption performance after 5 cycles. After the 5th cycle, the removal rates of Pb(II) and MB were still 85.6% and 86.2%, respectively, indicating that the material had a stable structure and well-preserved active sites after multiple adsorption-desorption operations.
[0066] The results show that the adsorbent material prepared by this invention has excellent recyclability and cycle stability, and is suitable for long-term repeated use.
[0067] Example 7 To verify the applicability of the adsorbent material prepared in this invention in complex real-world systems, a typical mineral processing wastewater simulation system was constructed to evaluate its adsorption performance. The simulated wastewater was based on the ionic composition of typical copper-lead-zinc ore wastewater, and the solution components were configured according to actual monitoring data. Specifically, it included 50 mg / L Pb(II), 50 mg / L Cu(II), 50 mg / L Zn(II), 100 mg / L MB, and a background electrolyte of 0.05 mol / L NaNO3 (saline wastewater) to simulate a high ionic strength environment. The pH of this wastewater system is typically between 3 and 9; in this embodiment, the pH was set to 5.
[0068] In the adsorption experiment, the adsorbent material prepared by mixing rice straw and sugarcane bagasse in Example 1 at a mass ratio of 1:1 was selected and added to the simulated wastewater at a solid-liquid ratio of (0.1–2.0) g:1 L. The adsorption temperature was 25 ℃ and the adsorption time was 30–180 min.
[0069] Specifically, in this embodiment, a solid-liquid ratio of 0.5 g:1 L and an adsorption time of 120 min were used. After the experiment, the supernatant was obtained by centrifugation, the residual concentration of each pollutant was measured, and the removal rate was calculated to evaluate the adsorption effect of the material in a simulated mineral processing wastewater system.
[0070] Table 7. Removal efficiency of adsorbent materials in the simulated mineral processing wastewater system.
[0071] As shown in Table 7, the adsorbent material prepared in this invention still exhibits excellent synergistic adsorption performance under the complex ionic background of mineral processing wastewater. The removal rates of Pb(II), Cu(II), Zn(II), and MB all exceed 83%, with the removal rate of Pb(II) reaching as high as 90.8%, indicating that the material still possesses good selectivity and adsorption stability under conditions of high ionic strength and multi-component coexistence.
[0072] The results demonstrate that the material of this invention is not only applicable to ideal experimental systems, but also maintains a high efficiency in pollutant removal under simulated real mineral processing wastewater conditions, exhibiting significant environmental adaptability and engineering application potential.
[0073] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for preparing a magnetically modified plant-derived alginate biochar adsorbent material, characterized in that, Includes the following steps: S1. Plant-derived biochar is obtained by drying, crushing and sieving plant-derived biomass waste and then pyrolyzing it. The biochar is then mixed with magnetic materials, β-cyclodextrin and organic acid crosslinking agents to form a composite slurry. The magnetic material is Fe3O4 nanoparticles, magnetic manganese oxide, magnetic nickel-iron oxide, or magnetic cobalt-iron oxide; the organic acid crosslinking agent is citric acid. S2. The composite slurry is dispersed and added to sodium alginate solution and stirred evenly. At room temperature, it is then added dropwise to calcium chloride solution to crosslink and form gel spheres. S3. After washing and freeze-drying the gel spheres, magnetically modified plant-derived alginate biochar adsorbent material is obtained.
2. The preparation method according to claim 1, characterized in that, In S1, the plant-derived biomass waste is a mixture of corn stalks, sugarcane bagasse, rice straw, and urban greening pruning waste in a mass ratio of 1:1:1:1; preferably, rice straw and sugarcane bagasse are mixed in a mass ratio of 1:
1. The drying, pulverizing, and sieving processes involve drying in an 80°C oven for 24 hours, pulverizing, and sieving through a 100-mesh sieve. The pyrolysis is carried out under oxygen-limited conditions, with a pyrolysis temperature of 250–400 °C and a time of 1–4 h; preferably, the pyrolysis temperature is 300 °C and the time is 2 h.
3. The preparation method according to claim 2, characterized in that, In S1, the magnetic material is MnFe2O3, NiFe2O4, or CoFe2O4; preferably NiFe2O4. The mass ratio of the magnetic material, biochar, and β-cyclodextrin is (0.5–1.5):1:(0.5–1.5); preferably 1:1:
1.
4. The preparation method according to claim 1, characterized in that, S1 also includes: adding a dispersing agent to make the mixture uniformly dispersed and combined; The dispersing agent is sodium dihydrogen phosphate and polyethylene glycol, with a mass ratio of 1:2.
5.
5. The preparation method according to claim 4, characterized in that, In S1, the organic acid crosslinking agent further includes: malic acid, tartaric acid, sodium citrate, or sodium malate; The amount of citric acid, malic acid, tartaric acid, sodium citrate, or sodium malate added is 1 to 5% of the total mass of the mixture, preferably 3%.
6. The preparation method according to claim 1, characterized in that, In S2, the dispersion process is a microwave-assisted dispersion process with a power of 100–200W, a processing temperature of 30–60℃, and a processing time of 30–90min. The preferred power is 136W, the processing temperature is 40℃, and the processing time is 60min.
7. The preparation method according to claim 1, characterized in that, In S2, the solid-liquid ratio of sodium alginate to composite slurry is (20–30) g: 1 L, the concentration of calcium chloride solution is 20 g / L, and the crosslinking time is 8–24 h; preferably, the crosslinking time is 12 h.
8. A method for synergistically treating a pollution system containing both heavy metals and organic dyes using a magnetically modified plant-derived alginate biochar adsorbent material prepared according to the methods described in claims 1 to 7, characterized in that... The adsorbent material was added to the polluted system at a solid-liquid ratio of (0.1–2.0) g:1 L, and the adsorption time was 30–180 min; preferably, the solid-liquid ratio was 0.5 g:1 L and the adsorption time was 120 min. The pollution system is a saline wastewater composed of Pb(II), Cu(II), Zn(II) and / or methylene blue, with a pH of 3–9.
9. The processing method according to claim 8, characterized in that, After adsorption is complete, the separated adsorbent material is placed in a mixed solution of 0.1 mol / L citric acid aqueous solution and methanol at a volume ratio of 1:1 for 1 h, and then washed with deionized water until the washing solution is neutral before freeze-drying to complete regeneration.
10. The processing method according to claim 8, characterized in that, Repeat the sampling of the polluting system 4-5 times until the emission standards are met.