Soil remediation drought-resistant material and preparation method thereof

Abstract

The invention discloses a soil remediation drought-resistant material and a preparation method thereof, and relates to the technical field of soil remediation. The soil remediation drought-resistant material is prepared from modified rice husk-based biochar, iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin, sodium alginate and calcium chloride, the modified rice hull based biochar is uniformly dispersed and embedded in a calcium alginate three-dimensional gel network to form a shell layer, and the core layer iron-cerium-zinc ternary metal oxide supported composite water retention adsorption resin is subjected to coating crosslinking, so that interface bonding and connection are enhanced, and a dual adsorption barrier with quick response and deep fixation is constructed; the high efficiency and stability of heavy metal particle repair are ensured, in addition, the shell layer not only participates in repair, but also is an intelligent water molecule regulation and control valve, the water retention performance of the core resin is regulated and enhanced, the mobility of the heavy metal particles during water shortage is further reduced, and the repair effect is deepened.

Description

Technical Field

[0001] This invention belongs to the field of soil remediation technology, specifically referring to a soil remediation drought-resistant material and its preparation method. Background Technology

[0002] With the rapid development of society, economy and modern industry, heavy metal production activities in industries such as electroplating, metallurgy and petrochemicals have increased significantly. The wastewater generated by these industries usually contains heavy metal ions such as nickel, copper, chromium, vanadium and lead, which are highly toxic, difficult to degrade and easy to bioaccumulate. If the discharge exceeds the standard or is not treated properly, it can easily cause serious harm to the environment and organisms. In addition, soil heavy metal pollution also seriously threatens ecological security and sustainable agricultural development due to its environmental persistence, chemical irreversibility and ecological accumulation.

[0003] When soil faces drought conditions, the existing heavy metal pollution problem often becomes more complex and severe. On the one hand, water shortage will cause drastic changes in the physical and chemical properties of the soil. Heavy metals that were originally bound to sulfides or adsorbed on organic matter are released and transformed from a stable residual state into a more active exchangeable and dissolved state, thereby increasing toxicity. On the other hand, the reduction of soil moisture leads to an increase in the concentration of heavy metal ions in the solution due to the reduction of solvent. In order to maintain survival, plants must absorb water and have to ingest higher concentrations of heavy metal solutions, further aggravating the pollution risk.

[0004] The existing technology currently has the following main problems:

[0005] Commonly used remediation materials generally have insufficient water retention capacity, making it difficult to effectively control the migration of heavy metals and limiting the improvement of soil remediation effects. Summary of the Invention

[0006] In view of the above situation and to overcome the defects of the prior art, the present invention proposes a soil remediation drought-resistant material, comprising the following components in parts by weight: 3-5 parts of modified rice husk-based biochar, 8-10 parts of iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin, 0.3-0.5 parts of sodium alginate, and 0.5-1.0 parts of calcium chloride.

[0007] The iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin is made from the following components in parts by weight: 3-5 parts of double-modified exchange resin, 13.5-14.5 parts of iron nitrate nonahydrate, 8.3-9.3 parts of cerium nitrate hexahydrate, and 3.6-4.6 parts of zinc nitrate hexahydrate.

[0008] The preparation method of the modified rice husk-based biochar specifically includes the following steps:

[0009] (1) Wash 90.0-100.0g of rice husks with deionized water, then dry them in an oven at 100℃ for 1-2 hours, pulverize them, and sieve them with a mesh size of 80-100 mesh. Place the resulting rice husk powder in a covered ceramic crucible, cover it, and place it in a muffle furnace at 600℃ for oxygen-deficient carbonization treatment for 2-3 hours. After natural cooling, remove it and wash it with deionized water until the filtrate is clear. Place the washed carbonized rice husk powder in an oven at 70℃ for 1-2 hours. The biochar made from rice husks has the characteristics of high silicon content and porous structure. This porous structure not only provides a large number of physical adsorption sites for heavy metal ions, but also adsorbs and stores a large amount of water, enhancing the soil's water retention capacity. At the same time, the amorphous silicon and carbonates it contains can form silicate or carbonate precipitates with heavy metals after dissolving in the soil solution, transforming heavy metals from an exchangeable state that is easily absorbed by plants into a stable, non-toxic residue state. Rice husk biochar can release soluble silicon and deposit it in plant epidermal cells to form a silicified cell layer, reducing water loss through transpiration from the cuticle, thus obtaining rice husk-based biochar.

[0010] (2) Dissolve tetrasodium iminodisuccinate in 500mL of deionized water and adjust the pH to 9.0. Make up the volume to 600mL to form a tetrasodium iminodisuccinate solution for later use. Then weigh 30.0-40.0g of the rice husk-based biochar described in step (1) and add it to the tetrasodium iminodisuccinate solution. Place it in a shaker at room temperature and shake for 20-24h at a shaking speed of 100-150rpm. After the reaction is complete, filter and wash the filter cake repeatedly with deionized water until the pH of the washing liquid is 7.0 and the conductivity is <50μS. / cm, and then the washed filter cake is placed in a 70℃ oven to dry for 1-2 hours. Tetrasodium iminodisuccinate is loaded onto rice husk-based biochar for modification treatment, so that the strong chelating ability of tetrasodium iminodisuccinate is combined with the porous structure of rice husk biochar, which greatly improves the stability and passivation ability of heavy metals in the soil, reduces the absorption and accumulation of heavy metals by crops, and the well-developed porous structure of rice husk-based biochar can play a water storage role after being applied to the soil, effectively absorbing and retaining water, reducing evaporation and seepage losses, thus obtaining modified rice husk-based biochar.

[0011] Preferably, in step (2), the amount of tetrasodium iminodisuccinate added is 10.0g. Tetrasodium iminodisuccinate is rich in carboxyl and amino groups, which can effectively complex heavy metal ions. Moreover, tetrasodium iminodisuccinate can maintain excellent chelation stability over a wide pH range, thus solving the problem of traditional chelating agents failing in high pH environments.

[0012] This invention also provides a method for preparing a soil remediation and drought-resistant material, specifically including the following steps:

[0013] S1. Add 1.6-1.8g of hydrogen-containing silicone oil and 6.8-7.2g of dichloromethane to nano-silica, heat at 35℃ for 30-50min, and vacuum dry at 0.090-0.095MPa and 60℃. The silicone oil reacts chemically with the hydroxyl groups on the surface of nano-silica, changing the surface of silica from hydrophilic to hydrophobic, thus improving its compatibility with the polymer matrix. The introduction of modified nano-silica can enhance the structural stability of the material and improve the water retention performance by adjusting the crosslinking density and hydrophilic-hydrophobic balance of the polymer. In addition, after adsorbing heavy metals, the rigid silica framework can maintain the basic structure of the material and prevent the chain segment collapse caused by the covering of organic active sites, thereby maintaining the water retention and repair capabilities of the material, and obtaining modified nano-silica powder.

[0014] S2. Add 0.3-0.5g gelatin, 0.03-0.05g hydroxypropyl methylcellulose, and 1.0-1.5g sodium chloride to 100mL deionized water and heat to 40-50℃ to dissolve. Set aside as the aqueous phase. In a beaker, add 6-8mL styrene and 1-2mL hydroxyethyl methacrylate sequentially, mix well, then add 6-8mL divinylbenzene and 5-8mL n-heptane, and stir for 10-20min. Then add 5.0-6.0g of the modified nano-silica powder described in step S1, and sonicate for 5-10min. Finally, add 0.1-0.2g benzoyl peroxide and stir for 5-10min to obtain the oil phase. Set aside as the oil phase. While stirring at 250rpm, slowly add the oil phase dropwise to the aqueous phase at a rate of 1mL / min. Heat to 80℃ and maintain the temperature while stirring for 3-4 minutes. h, filtration, the solid product was washed three times with deionized water and dried. Modified nano-silica powder was uniformly dispersed in the polymer network as a rigid filler, forming a spherical structure with high cross-linking degree, multi-level porous structure and rich in hydroxyl functional groups. This hybrid resin material adsorbs exchangeable heavy metals in the soil solution into the resin through multiple adsorption mechanisms such as chemical complexation, physical adsorption, and cation exchange, effectively reducing their migration. At the same time, the porous structure of the resin can store water, and hydrophilic groups such as hydroxyl groups enhance water affinity. Both improve drought resistance, while the spherical shape helps to improve soil aggregate structure, increase porosity, and reduce water evaporation. In addition, the modified nano-silica powder can prevent the polymer chain segments from collapsing after water absorption, ensuring that the adsorption sites are continuously exposed, further maintaining the adsorption and water retention functions of the material, resulting in resin white spheres.

[0015] S3. Weigh 6.0-8.0g of the resin white balls described in step S2 and place them in a 250mL three-necked flask. Add 8mL of a mixed solvent of dichloromethane and 2mL of 1,2-dichloroethane. Allow the mixture to swell at room temperature for 10-20 minutes. While cooling in an ice-water bath, slowly add a 90% sulfuric acid solution, controlling the system temperature to not exceed 30°C during the dropwise addition. After the dropwise addition is complete, stir the mixture at room temperature for 1-2 hours, then raise the temperature to 60°C and react for 1-2 hours. Finally, raise the temperature to 80°C and react for 2-3 hours. After the reaction is complete, allow it to cool naturally to room temperature. Stir the mixture in a fume hood for 50-60 minutes to ensure complete evaporation of the dichloromethane. Place the mixture in an ice-water bath and slowly add 40mL of a 50% sulfuric acid solution, maintaining the system temperature below 35°C. Pour off the acid solution and place the resin in a saturated food container at 0°C. The resin was washed with deionized water in brine until the pH was neutral. Then, the resin was transferred to a beaker and a 5% (w / w) dilute nitric acid solution was added. The mixture was stirred in a 50°C water bath for 0.5-1 h. The acid solution was poured off and the resin was washed repeatedly with deionized water until the pH was neutral. The oxidized and washed resin balls were then transferred into an adsorption column and washed sequentially with a 5% (w / w) sodium hydroxide solution, deionized water, a 5% (w / w) sulfuric acid solution, and deionized water. This process was repeated three times. The resin balls were then filtered and dried. The double-modified ion exchange resin prepared by this process is a strong acid cation exchange resin. Through sulfonation and oxidation, sulfonic acid groups and oxygen-containing functional groups were introduced, while the porous structure and water retention function of the original resin balls were retained. This allows the resin to effectively fix heavy metals under dry conditions and reduce the migration of heavy metals.

[0016] S4. Add ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate sequentially to 100 mL of deionized water to obtain a composite nitrate solution. Weigh 3.0-5.0 g of the double-modified exchange resin described in step S3 and immerse it in the composite nitrate solution. Place the solution on a shaker at 100 rpm for 1-2 hours at room temperature. Filter, collect the solid, and immerse it in 100 mL of 5% sodium hydroxide solution. React in a 40°C water bath for 4-6 hours. Filter again, and wash the solid product with deionized water. When the pH of the eluent is neutral, it is first dried at 60℃ and then heat-treated at 200℃ for 1-2 hours. The iron-cerium-zinc ternary metal oxide nanoparticles are firmly loaded on the inner surface of the pores of the double-modified exchange resin. This ternary metal oxide has more lattice defects and active sites, providing a strong coordination adsorption function. It exhibits a strong affinity for various heavy metal cations such as cadmium, lead, copper, and zinc, as well as oxygen-containing anions in the soil, effectively reducing the migration of heavy metals, and thus obtaining an iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin.

[0017] S5. Weigh 8.0-10.0g of the iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin described in step S4, immerse it in 50mL of anhydrous ethanol to swell for 10min, filter, and quickly rinse once with deionized water to obtain pretreated resin. Add 0.3-0.5g of sodium alginate to 50mL of 60-70℃ hot water, stir until completely dissolved, cool to room temperature, add 3.0-5.0g of modified rice husk-based biochar, and ultrasonically disperse for 20-30min to form a biochar suspension for later use. Then add the pretreated resin to the biochar suspension, place it on a shaker, and shake at room temperature for 2-4h. The mixture was stirred at 100-200 rpm, filtered, and the solid material was collected and immersed in 50 mL of 1-2% calcium chloride solution. It was stirred at 30 rpm for 40-50 min, filtered again, and the product was washed twice with deionized water. It was then dried at 40℃ for 8-10 h, followed by drying at 60℃ for 4-6 h. The product was then pulverized, and the modified rice husk-based biochar was uniformly dispersed and embedded in the cross-linked calcium alginate three-dimensional gel network as an outer shell. This shell layer encapsulated and cross-linked with the iron-cerium-zinc ternary metal oxide-supported composite water-retaining and adsorbing resin, strengthening the interfacial bonding and connection. Oxide-supported composite water-retaining adsorption resin serves as the core layer, possessing not only high water absorption and chemisorption sites but also sufficient mechanical strength to prevent material breakage under external forces. The outer shell, with its abundant pores and functional groups, directly faces the external environment, enabling rapid capture and adsorption of heavy metal ions from the soil solution. Ions penetrating the shell enter the inner resin layer, where they are further immobilized by ion exchange with sulfonic acid groups and coordination adsorption of iron, cerium, and zinc oxides. This ensures the stability and irreversibility of heavy metal adsorption. Simultaneously, the integration of modified rice husk-based biochar into the calcium alginate gel network introduces micropores and channels into the gel, enhancing its effectiveness. The calcium alginate gel acts as a smart water molecule regulating valve, allowing water to pass through and be absorbed and stored by the core resin when the soil is moist. When the soil is dry, it slows down the outward diffusion of internal water, achieving slow release and regulating and enhancing the water retention performance of the core resin. Furthermore, both biochar and calcium alginate are soil-like organic matter components that can bind tightly with soil particles, avoiding the interfacial voids between pure synthetic resin and soil. The outer shell also buffers the physical compression of plant roots when the resin absorbs water and expands, eliminating the inhibitory effect of pure resin on seedling growth, thus obtaining a soil remediation and drought-resistant material.

[0018] Preferably, in step S1, the amount of nano-silica used is 20.0-24.0g, with a particle size of 30nm. As rigid particles, nano-silica constructs a compressive-resistant skeleton, increasing the mechanical strength and structural stability of the resin material. This allows it to maintain open pores after absorbing water and swelling, and it is not easily flattened under soil load, thus ensuring the durability of the water-holding space. Nano-silica can also serve as a carrier, as its nanoscale size and uneven surface defect sites provide a large number of nucleation sites for subsequent metal oxides.

[0019] Preferably, in step S3, the amount of 90% sulfuric acid solution added is 50-60 mL. When the sulfuric acid solution acts on the styrene-divinylbenzene copolymer under heating conditions, sulfonic acid groups can be introduced onto the benzene ring. The sulfonic acid groups not only provide exchange sites for the repair of heavy metals, but also form continuous ion exchange regions inside the resin, ensuring rapid diffusion and exchange of heavy metal ions. At the same time, as a strong hydrophilic group, the sulfonic acid groups greatly improve the water absorption of the resin.

[0020] Preferably, in step S3, the amount of dilute nitric acid solution added is 80-100 mL. Dilute nitric acid can oxidize the sulfonated resin, and the introduced phenolic hydroxyl groups provide additional complexation sites to form stable chelates with heavy metals, thereby improving the immobilization efficiency. The introduced nitro groups enhance the polarity and hydrophilicity of the resin, and improve water wetting and transfer.

[0021] Preferably, in step S4, the amounts of ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate added are 13.5-14.5g, 8.3-9.3g, and 3.6-4.6g, respectively. The oxides of iron, cerium, and zinc have a large number of surface hydroxyl groups, which can form stable complexes or surface precipitates with heavy metal ions, significantly reducing the desorption rate of heavy metals, achieving true passivation and fixation, and preventing secondary pollution. As powerful adsorption sites, the iron, cerium, and zinc oxides protect the hydrophilic groups such as hydroxyl and sulfonic acid groups on the polymer backbone from being occupied by heavy metals, ensuring that the water-holding function of the material is maintained for a long time.

[0022] The beneficial effects achieved by this invention are as follows:

[0023] This invention utilizes a modified rice husk-based biochar layer, uniformly dispersed and embedded within a calcium alginate three-dimensional gel network to form an outer shell. This outer shell layer, along with a core layer of iron-cerium-zinc ternary metal oxide-supported composite water-retaining adsorption resin, is then coated and cross-linked. This strengthens interfacial bonding and connectivity, constructing a rapid-response, deeply immobilized dual adsorption barrier. This ensures high efficiency and stability in the remediation of heavy metal particles. Furthermore, the outer shell layer not only participates in the remediation process but also acts as an intelligent water molecule regulating valve, adjusting and enhancing the water-holding capacity of the core resin. This further reduces the migration of heavy metal particles during water scarcity, thus deepening the remediation effect. The modified rice husk-based biochar is further modified by loading tetrasodium iminodisuccinate onto the biochar. The strong chelating ability of tetrasodium iminodisuccinate, combined with the porous structure of rice husk biochar, significantly enhances the stabilization and passivation of heavy metals in the soil. The chelating action of tetrasodium iminodisuccinate can stably fix heavy metals on the surface of biochar, reducing their migration and bioavailability, thereby reducing the absorption and accumulation of heavy metals by crops. Simultaneously, the well-developed porous structure of rice husk-based biochar, when applied to the soil, can act as a water-retaining agent, effectively absorbing and retaining moisture, reducing evaporation and seepage losses. The loaded tetrasodium iminodisuccinate molecules are hydrophilic, further improving the wettability of the biochar surface, which is beneficial for water adsorption, thus synergistically enhancing the drought resistance of the soil. The iron-cerium-zinc ternary metal oxide-supported composite water-retaining agent... In the adsorption resin, a dual-modified exchange resin is first obtained through sulfonation and oxidation modification. This process introduces sulfonic acid groups and oxygen-containing functional groups while retaining the porous structure and water-retention function of the original resin spheres. The sulfonic acid groups provide strong cation exchange capacity, endowing the resin with a high capacity for heavy metal ion exchange. Phenolic hydroxyl groups, nitro groups, and other oxygen-containing functional groups enhance hydrophilicity and heavy metal complexation ability. The two work synergistically to enhance the water-holding capacity of the resin, enabling it to effectively fix heavy metals even under drought conditions. Next, iron-cerium-zinc ternary metal oxide nanoparticles are firmly loaded onto the inner surface of the pores of the dual-modified exchange resin. These ternary metal oxides have more lattice defects and active sites, providing strong coordination adsorption capabilities for substances such as cadmium and lead in soil. Copper, zinc, and other heavy metal cations and oxygen-containing anions exhibit strong affinity, effectively reducing the migration of heavy metals. Simultaneously, iron-cerium-zinc oxides serve as powerful adsorption sites, sharing some of the heavy metal adsorption workload and protecting the hydrophilic groups such as hydroxyl and sulfonic acid groups on the polymer backbone from being occupied by heavy metals. Therefore, the dual-modified exchange resin maintains high water retention and good remediation performance under the protection of the ternary metal oxides. This invention uses modified rice husk-based biochar, iron-cerium-zinc ternary metal oxide-supported composite water-retaining adsorption resin, sodium alginate, and calcium chloride to create a soil remediation and drought-resistant material. This not only improves the material's water retention but also effectively controls heavy metal migration, further enhancing the soil remediation effect. Attached Figure Description

[0024] Figure 1The figures show the water-holding performance results of Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0025] Figure 2 The graph shows the adsorption results of Examples 1-4 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0028] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; unless otherwise specified, the experimental materials used in the following embodiments are all purchased from commercial channels.

[0029] Example 1

[0030] This embodiment proposes a soil remediation and drought-resistant material, comprising the following components in parts by weight: 4 parts modified rice husk-based biochar, 9 parts iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin, 0.4 parts sodium alginate, and 0.75 parts calcium chloride.

[0031] The iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin is made from the following components in parts by weight: 4 parts of double-modified exchange resin, 14 parts of iron nitrate nonahydrate, 8.8 parts of cerium nitrate hexahydrate, and 4.1 parts of zinc nitrate hexahydrate.

[0032] The preparation method of modified rice husk-based biochar specifically includes the following steps:

[0033] (1) 95.0g of rice husks were first washed with deionized water, then dried in an oven at 100℃ for 1.5h, pulverized, and sieved with a mesh size of 90. The resulting rice husk powder was placed in a covered ceramic crucible, covered, and placed in a muffle furnace at 600℃ for anaerobic carbonization treatment for 2.5h. After natural cooling, it was taken out and washed with deionized water until the filtrate was clear. The washed carbonized rice husk powder was placed in an oven at 70℃ for 1.5h. The biochar made from rice husks has high silicon content and porous structure. The structure not only provides a large number of physical adsorption sites for heavy metal ions, but also adsorbs and stores a large amount of water, enhancing the soil's water retention capacity. At the same time, the amorphous silicon and carbonates it contains can dissolve in the soil solution and form silicate or carbonate precipitates with heavy metals, transforming heavy metals from an exchangeable state that is easily absorbed by plants into a stable, non-toxic residue state. Rice husk biochar can release soluble silicon and deposit it in plant epidermal cells to form a silicified cell layer, reducing water loss through cuticle transpiration, thus obtaining rice husk-based biochar.

[0034] (2) Dissolve tetrasodium iminodisuccinate in 500mL of deionized water and adjust the pH to 9.0. The amount of tetrasodium iminodisuccinate added is 10.0g. Tetrasodium iminodisuccinate is rich in carboxyl and amino groups, which can effectively complex heavy metal ions. Moreover, tetrasodium iminodisuccinate can maintain excellent chelation stability over a wide pH range, solving the problem of traditional chelating agents failing in high pH environments. Adjust the volume to 600mL to form a tetrasodium iminodisuccinate solution for later use. Then weigh 35.0g of the rice husk-based biochar described in step (1) and add it to the tetrasodium iminodisuccinate solution. Place it in a shaker at room temperature and shake for 22h at a shaking speed of 125. After the reaction was completed at rpm, the mixture was filtered and the filter cake was repeatedly washed with deionized water until the pH of the washing liquid was 7.0 and the conductivity was <50μS / cm. Then, the washed filter cake was dried in a 70℃ oven for 1.5h. Tetrasodium iminodisuccinate was loaded onto rice husk-based biochar for modification treatment, so that the strong chelating ability of tetrasodium iminodisuccinate combined with the porous structure of rice husk biochar, which greatly improved the stability and passivation ability of heavy metals in the soil, reduced the absorption and accumulation of heavy metals by crops, and the well-developed porous structure of rice husk-based biochar could play a water storage role after being applied to the soil, effectively absorbing and retaining water, reducing evaporation and seepage losses, thus obtaining modified rice husk-based biochar.

[0035] This embodiment provides a method for preparing a soil remediation and drought-resistant material, which specifically includes the following steps:

[0036] S1. 1.7g of hydrogen-containing silicone oil and 7.0g of dichloromethane were poured into nano-silica. The amount of nano-silica used was 22.0g, with a particle size of 30nm. Nano-silica, as rigid particles, constructed a compressive-resistant skeleton, increasing the mechanical strength and structural stability of the resin material. This allowed it to maintain open pores after absorbing water and swelling, preventing it from being flattened under soil load, thus ensuring the durability of the water-holding space. Nano-silica can also serve as a carrier; its nanoscale size and uneven surface defects provide numerous nucleation sites for subsequent metal oxides. The reaction was carried out at 35℃ for 40 minutes. Vacuum drying at 0.093 MPa and 60℃ causes a chemical reaction between silicone oil and the hydroxyl groups on the surface of nano-silica, changing the silica surface from hydrophilic to hydrophobic and improving its compatibility with the polymer matrix. The introduction of modified nano-silica can enhance the structural stability of the material and improve its water retention performance by adjusting the crosslinking density and hydrophilic-hydrophobic balance of the polymer. In addition, after adsorbing heavy metals, the rigid silica framework can maintain the basic structure of the material and prevent the chain segment collapse caused by the covering of organic active sites, thereby maintaining the water retention and repair capabilities of the material, resulting in modified nano-silica powder.

[0037] S2. Add 0.4g gelatin, 0.04g hydroxypropyl methylcellulose, and 1.25g sodium chloride to 100mL deionized water and heat to 45℃ to dissolve. Set aside as the aqueous phase. In a beaker, add 7mL styrene and 1.5mL hydroxyethyl methacrylate sequentially, mix well, then add 7mL divinylbenzene and 6.5mL n-heptane, and stir for 15min. Then add 5.5g of the modified nano-silica powder described in step S1, and sonicate for 7.5min. Finally, add 0.15g benzoyl peroxide and stir for 7.5min to obtain the oil phase. Set aside as the oil phase. While stirring at 250rpm, slowly add the oil phase dropwise to the aqueous phase at a rate of 1mL / min. Heat to 80℃, maintain the temperature and stir for 3.5h, filter, and wash the solid product with deionized water. After three drying cycles, the modified nano-silica powder, acting as a rigid filler, is uniformly dispersed in the polymer network, forming a spherical structure with high cross-linking degree, hierarchical pore structure, and rich in hydroxyl functional groups. This hybrid resin material adsorbs exchangeable heavy metals in the soil solution into the resin interior through multiple adsorption mechanisms such as chemical complexation, physical adsorption, and cation exchange, effectively reducing their migration. At the same time, the porous structure of the resin can store water, and the hydrophilic groups such as hydroxyl groups enhance water affinity. Both of these factors improve drought resistance, while the spherical shape helps improve soil aggregate structure, increase porosity, and reduce water evaporation. In addition, the modified nano-silica powder can prevent polymer chain collapse after water absorption, ensuring continuous exposure of adsorption sites and further maintaining the adsorption and water retention functions of the material, resulting in resin white spheres.

[0038] S3. Weigh 7.0g of the resin white balls described in step S2 and place them in a 250mL three-necked flask. Add 8mL of a mixed solvent of dichloromethane and 2mL of 1,2-dichloroethane. Allow the mixture to swell at room temperature for 15min. Under ice-water bath cooling, slowly add a 90% sulfuric acid solution, controlling the system temperature to not exceed 30℃ during the addition process. The amount of 90% sulfuric acid solution added is 55mL. When the sulfuric acid solution acts on the styrene-divinylbenzene copolymer under heating conditions, sulfonic acid groups can be introduced onto the benzene ring. Sulfonic acid groups not only provide cross-linking for the remediation of heavy metals... The site-changing process also creates continuous ion exchange regions within the resin, ensuring rapid diffusion and exchange of heavy metal ions. Simultaneously, the sulfonic acid groups, as strongly hydrophilic groups, significantly enhance the resin's water absorption. After the addition is complete, the mixture is stirred at room temperature for 1.5 hours, then heated to 60°C for another 1.5 hours, and finally heated to 80°C for 2.5 hours. After the reaction, it is allowed to cool naturally to room temperature, then stirred openly in a fume hood for 55 minutes to ensure complete dichloromethane evaporation. The mixture is then placed in an ice-water bath, and 40 mL of a 50% sulfuric acid solution is slowly added, maintaining the system temperature below 35°C. At ℃, pour off the acid solution and place the resin in saturated saline solution at 0℃. Wash with deionized water until the pH is neutral. Then transfer the resin to a beaker and add 90 mL of 5% (w / w) dilute nitric acid solution. The dilute nitric acid can oxidize the sulfonated resin, and the introduced phenolic hydroxyl groups provide additional complexing sites to form stable chelates with heavy metals, improving immobilization efficiency. The introduced nitro groups enhance the polarity and hydrophilicity of the resin, improving water wetting and transfer. Stir the reaction in a 50℃ water bath for 0.75 h, pour off the acid solution, and wash repeatedly with deionized water until the pH is neutral. To ensure neutrality, the oxidized and washed resin balls were transferred into the adsorption column and washed sequentially with a 5% sodium hydroxide solution, deionized water, a 5% sulfuric acid solution, and deionized water. After repeating this process three times, the resin balls were filtered and dried. The double-modified cation exchange resin prepared by this process is a strong acid cation exchange resin. Through sulfonation and oxidation, sulfonic acid groups and oxygen-containing functional groups were introduced, while the porous structure and water retention function of the original resin balls were retained. This allows the resin to effectively fix heavy metals under drought conditions and reduce the migration of heavy metals, thus obtaining the double-modified cation exchange resin.

[0039] S4. Add ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate sequentially to 100 mL of deionized water. The amounts of ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate added are 14.0 g, 8.8 g, and 4.1 g, respectively. The oxides of iron, cerium, and zinc have a large number of surface hydroxyl groups, which can form stable complexes or surface precipitates with heavy metal ions, significantly reducing the desorption rate of heavy metals, achieving true passivation and fixation, and preventing secondary pollution. The iron, cerium, and zinc oxides act as strong adsorption sites, protecting the hydrophilic groups such as hydroxyl and sulfonic acid groups on the polymer backbone from being occupied by heavy metals, ensuring the long-term maintenance of the material's water-holding capacity. The resulting composite nitrate solution is then ready for use. Weigh 4.0 g of the double-modified exchange resin described in step S3 and immerse it in the composite nitrate solution. The solution was placed on a shaker at room temperature and shaken at 100 rpm for 1.5 h. After filtration, the solid was collected and immersed in 100 mL of 5% sodium hydroxide solution. The reaction was carried out in a water bath at 40 °C for 5 h. After filtration, the solid product was washed with deionized water until the pH of the eluent was neutral. It was dried at 60 °C and then heat-treated at 200 °C for 1.5 h. The iron-cerium-zinc ternary metal oxide nanoparticles were firmly loaded on the inner surface of the pores of the double-modified exchange resin. This ternary metal oxide has more lattice defects and active sites, providing a strong coordination adsorption function. It shows a strong affinity for various heavy metal cations such as cadmium, lead, copper, and zinc, as well as oxygen-containing anions in the soil, effectively reducing the migration of heavy metals. The iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin was obtained.

[0040] S5. Weigh 9.0g of the iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin described in step S4, immerse it in 50mL of anhydrous ethanol to swell for 10min, filter, and quickly rinse once with deionized water to obtain pretreated resin. Add 0.4g of sodium alginate to 50mL of 65℃ hot water, stir until completely dissolved, cool to room temperature, add 4.0g of modified rice husk-based biochar, and ultrasonically disperse for 25min to form a biochar suspension for later use. Then add the pretreated resin to the biochar suspension, place it on a shaker, and shake at room temperature for 3h at a shaking speed of 150rpm. Filter. The solid material was collected and immersed in 50 mL of 1.5% calcium chloride solution, stirred at 30 rpm for 45 min, filtered, and the product was washed twice with deionized water. It was then dried at 40℃ for 9 h and then at 60℃ for 5 h, pulverized, and sieved through a 30-mesh screen. The modified rice husk-based biochar was uniformly dispersed and embedded in the cross-linked calcium alginate three-dimensional gel network as an outer shell layer, encapsulating and cross-linking with the iron-cerium-zinc ternary metal oxide-supported composite water-retaining adsorption resin, thus strengthening the interfacial bonding and connection. The iron-cerium-zinc ternary metal oxide-supported composite water-retaining adsorption resin serves as the core. The outer layer not only possesses high water absorption and chemical adsorption sites but also provides sufficient mechanical strength to prevent material breakage under external forces. The outer shell, with its abundant pores and functional groups, directly faces the external environment, enabling rapid capture and adsorption of heavy metal ions from the soil solution. Ions penetrating the shell enter the inner resin layer, where they are further immobilized by ion exchange of sulfonic acid groups and coordination adsorption of iron, cerium, and zinc metal oxides. This ensures the stability and irreversibility of heavy metal adsorption. Simultaneously, the modified rice husk-based biochar, embedded in the calcium alginate gel network, introduces micropores and channels into the gel, increasing the entry of water into the core resin layer. The lipid channel, calcium alginate gel, acts as a smart water molecule regulating valve. When the soil is moist, it allows water to pass through and be absorbed and stored by the core resin. When the soil is dry, it slows down the outward diffusion of internal water, achieving slow release. This regulates and enhances the water retention performance of the core resin. Furthermore, both biochar and calcium alginate are soil-like organic matter components that can bind tightly with soil particles, avoiding the interfacial voids between pure synthetic resin and soil. The outer shell also buffers the physical compression of plant roots when the resin absorbs water and expands, eliminating the inhibitory effect of pure resin on seedling growth, thus obtaining a soil remediation and drought-resistant material.

[0041] Example 2

[0042] This embodiment proposes a soil remediation and drought-resistant material, comprising the following components in parts by weight: 5 parts modified rice husk-based biochar, 10 parts iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin, 0.5 parts sodium alginate, and 1.0 part calcium chloride.

[0043] The iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin is made from the following components in parts by weight: 5 parts of double-modified exchange resin, 14.5 parts of iron nitrate nonahydrate, 9.3 parts of cerium nitrate hexahydrate, and 4.6 parts of zinc nitrate hexahydrate.

[0044] The preparation method of modified rice husk-based biochar specifically includes the following steps:

[0045] (1) 100.0g of rice husks were first washed with deionized water, then dried in an oven at 100℃ for 2 hours, pulverized, and sieved with a mesh size of 100 mesh. The resulting rice husk powder was placed in a covered ceramic crucible, covered, and placed in a muffle furnace at 600℃ for anaerobic carbonization treatment for 3 hours. After natural cooling, it was taken out and washed with deionized water until the filtrate was clear. The washed carbonized rice husk powder was placed in an oven at 70℃ for 2 hours. The biochar made from rice husks has high silicon content and porous structure. This porous structure Not only does it provide a large number of physical adsorption sites for heavy metal ions, but it can also adsorb and store a large amount of water, enhancing the soil's water retention capacity. At the same time, the amorphous silicon and carbonates it contains can dissolve in the soil solution and form silicate or carbonate precipitates with heavy metals, transforming heavy metals from an exchangeable state that is easily absorbed by plants into a stable, non-toxic residue state. Rice husk biochar can release soluble silicon and deposit it in plant epidermal cells, forming a silicified cell layer, reducing water loss through transpiration from the cuticle, thus obtaining rice husk-based biochar.

[0046] (2) Dissolve tetrasodium iminodisuccinate in 500mL of deionized water and adjust the pH to 9.0. The amount of tetrasodium iminodisuccinate added is 10.0g. Tetrasodium iminodisuccinate is rich in carboxyl and amino groups, which can effectively complex heavy metal ions. Moreover, tetrasodium iminodisuccinate can maintain excellent chelation stability over a wide pH range, solving the problem of traditional chelating agents failing in high pH environments. Adjust the volume to 600mL to form a tetrasodium iminodisuccinate solution for later use. Then weigh 40.0g of the rice husk-based biochar described in step (1) and add it to the tetrasodium iminodisuccinate solution. Place it in a shaker at room temperature and shake for 24h at a shaking speed of 15. After the reaction was completed at 0 rpm, the mixture was filtered and the filter cake was repeatedly washed with deionized water until the pH of the washing liquid was 7.0 and the conductivity was <50 μS / cm. Then, the washed filter cake was dried in a 70℃ oven for 2 hours. Tetrasodium iminodisuccinate was loaded onto rice husk-based biochar for modification. This combined the strong chelating ability of tetrasodium iminodisuccinate with the porous structure of rice husk biochar, which greatly improved the stability and passivation of heavy metals in the soil and reduced the absorption and accumulation of heavy metals by crops. The well-developed porous structure of rice husk-based biochar can play a water storage role after being applied to the soil, effectively absorbing and retaining water and reducing evaporation and seepage losses, thus obtaining modified rice husk-based biochar.

[0047] This embodiment provides a method for preparing a soil remediation and drought-resistant material, which specifically includes the following steps:

[0048] S1. 1.8g of hydrogen-containing silicone oil and 7.2g of dichloromethane were poured into nano-silica. The amount of nano-silica used was 24.0g, with a particle size of 30nm. Nano-silica, as rigid particles, constructed a compressive-resistant skeleton, increasing the mechanical strength and structural stability of the resin material. This allowed it to maintain open pores after absorbing water and swelling, preventing it from being flattened under soil load, thus ensuring the durability of the water-holding space. Nano-silica can also serve as a carrier; its nanoscale size and uneven surface defects provide numerous nucleation sites for subsequent metal oxides. The reaction was heated at 35℃ for 50 minutes. Vacuum drying at 0.095 MPa and 60℃ causes a chemical reaction between silicone oil and the hydroxyl groups on the surface of nano-silica, changing the silica surface from hydrophilic to hydrophobic and improving its compatibility with the polymer matrix. The introduction of modified nano-silica can enhance the structural stability of the material and improve its water retention performance by adjusting the crosslinking density and hydrophilic-hydrophobic balance of the polymer. In addition, after adsorbing heavy metals, the rigid silica framework can maintain the basic structure of the material and prevent the chain segment collapse caused by the covering of organic active sites, thereby maintaining the water retention and repair capabilities of the material, resulting in modified nano-silica powder.

[0049] S2. Add 0.5g gelatin, 0.05g hydroxypropyl methylcellulose, and 1.5g sodium chloride to 100mL deionized water and heat to 50℃ to dissolve. Set aside as the aqueous phase. In a beaker, add 8mL styrene and 2mL hydroxyethyl methacrylate sequentially, mix well, then add 8mL divinylbenzene and 8mL n-heptane, and stir for 20min. Then add 6.0g of the modified nano-silica powder described in step S1, and sonicate for 10min. Finally, add 0.2g benzoyl peroxide and stir for 10min to obtain the oil phase. Set aside as the oil phase. While stirring at 250rpm, slowly add the oil phase dropwise to the aqueous phase at a rate of 1mL / min. Heat to 80℃, maintain the temperature and stir for 4h, filter, wash the solid product three times with deionized water, and dry. Modified nano-silica powder, as a rigid filler, is uniformly dispersed in a polymer network, forming a spherical structure with high cross-linking degree, hierarchical pore structure, and rich in hydroxyl functional groups. This hybrid resin material adsorbs exchangeable heavy metals in the soil solution into the resin through multiple adsorption mechanisms such as chemical complexation, physical adsorption, and cation exchange, effectively reducing their migration. At the same time, the porous structure of the resin can store water, and hydrophilic groups such as hydroxyl groups enhance water affinity. Both of these enhance drought resistance. The spherical shape helps to improve soil aggregate structure, increase porosity, and reduce water evaporation. In addition, the modified nano-silica powder can prevent polymer chain collapse after water absorption, ensuring continuous exposure of adsorption sites, further maintaining the adsorption and water retention functions of the material, resulting in resin white spheres.

[0050] S3. Weigh 8.0g of the resin white balls described in step S2 and place them in a 250mL three-necked flask. Add 8mL of a mixed solvent of dichloromethane and 2mL of 1,2-dichloroethane. Allow the mixture to swell at room temperature for 20min. While cooling in an ice-water bath, slowly add a 90% sulfuric acid solution, controlling the system temperature to not exceed 30℃ during the addition process. The amount of 90% sulfuric acid solution added is 60mL. When the sulfuric acid solution acts on the styrene-divinylbenzene copolymer under heating conditions, it can introduce sulfonic acid groups onto the benzene ring. Sulfonic acid groups not only provide... The addition of exchange sites allows for the formation of continuous ion exchange regions within the resin, ensuring rapid diffusion and exchange of heavy metal ions. Simultaneously, the sulfonic acid groups, as strong hydrophilic groups, significantly enhance the resin's water absorption. After the addition is complete, the mixture is stirred at room temperature for 2 hours, then heated to 60°C for another 2 hours, and finally heated to 80°C for 3 hours. After the reaction, the mixture is allowed to cool naturally to room temperature and stirred openly in a fume hood for 60 minutes to confirm complete dichloromethane evaporation. The mixture is then placed in an ice-water bath, and 40 mL of a 50% sulfuric acid solution is slowly added, maintaining the system temperature below 35°C. Pour off the acid solution and place the resin in saturated saline solution at 0°C. Wash with deionized water until the pH is neutral. Then transfer the resin to a beaker and add 100 mL of 5% (w / w) dilute nitric acid solution. The dilute nitric acid can oxidize the sulfonated resin, and the introduced phenolic hydroxyl groups provide additional complexing sites to form stable chelates with heavy metals, improving immobilization efficiency. The introduced nitro groups enhance the polarity and hydrophilicity of the resin, improving water wetting and transfer. Stir the reaction in a 50°C water bath for 1 hour. Pour off the acid solution and wash repeatedly with deionized water until the pH is neutral. The oxidized and washed resin balls were transferred into an adsorption column and washed sequentially with 5% sodium hydroxide solution, deionized water, 5% sulfuric acid solution, and deionized water. After repeating the process three times, the resin balls were filtered and dried. The resulting double-modified cation exchange resin is a strong acid cation exchange resin. Through sulfonation and oxidation, sulfonic acid groups and oxygen-containing functional groups were introduced, while the porous structure and water retention function of the original resin balls were retained. This allows the resin to effectively fix heavy metals under drought conditions and reduce the migration of heavy metals, thus obtaining the double-modified cation exchange resin.

[0051] S4. Add ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate sequentially to 100 mL of deionized water. The amounts of ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate added are 14.5 g, 9.3 g, and 4.6 g, respectively. The oxides of iron, cerium, and zinc have a large number of surface hydroxyl groups, which can form stable complexes or surface precipitates with heavy metal ions, significantly reducing the desorption rate of heavy metals, achieving true passivation and fixation, and preventing secondary pollution. The iron, cerium, and zinc oxides act as strong adsorption sites, protecting the hydrophilic groups such as hydroxyl and sulfonic acid groups on the polymer backbone from being occupied by heavy metals, ensuring the long-term maintenance of the material's water-holding capacity. A composite nitrate solution is obtained for later use. Weigh 5.0 g of the double-modified exchange resin described in step S3 and immerse it in the composite nitrate solution. In an acid salt solution, the mixture was placed on a shaker at 100 rpm for 2 hours at room temperature. After filtration, the solid was collected and immersed in 100 mL of 5% sodium hydroxide solution. The mixture was then reacted in a water bath at 40°C for 6 hours. After filtration, the solid product was washed with deionized water until the pH of the eluent was neutral. It was then dried at 60°C and heat-treated at 200°C for 2 hours. Iron-cerium-zinc ternary metal oxide nanoparticles were firmly loaded on the inner surface of the pores of the double-modified exchange resin. This ternary metal oxide has more lattice defects and active sites, providing strong coordination adsorption function. It exhibits a strong affinity for various heavy metal cations such as cadmium, lead, copper, and zinc, as well as oxygen-containing anions in the soil, effectively reducing the migration of heavy metals. This yields an iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin.

[0052] S5. Weigh 10.0g of the iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin described in step S4, immerse it in 50mL of anhydrous ethanol to swell for 10min, filter, and quickly rinse once with deionized water to obtain pretreated resin. Add 0.5g of sodium alginate to 50mL of 70℃ hot water, stir until completely dissolved, cool to room temperature, add 5.0g of modified rice husk-based biochar, and ultrasonically disperse for 30min to form a biochar suspension for later use. Then add the pretreated resin to the biochar suspension, place it on a shaker, and shake at room temperature for 4h at a shaking speed of 200rpm. The solid material was collected by filtration and immersed in 50 mL of 2% calcium chloride solution. The mixture was stirred at 30 rpm for 50 min, filtered, and the product was washed twice with deionized water. It was then dried at 40℃ for 10 h and then at 60℃ for 6 h. The product was pulverized and sieved through a 40-mesh screen. The modified rice husk-based biochar was uniformly dispersed and embedded in the cross-linked calcium alginate three-dimensional gel network as an outer shell layer. This layer encapsulated and cross-linked with the iron-cerium-zinc ternary metal oxide-supported composite water-retaining adsorption resin, strengthening the interfacial bonding and connection. The iron-cerium-zinc ternary metal oxide-supported composite water-retaining adsorption resin served as the core. The outer layer not only possesses high water absorption and chemical adsorption sites but also provides sufficient mechanical strength to prevent material breakage under external forces. The outer shell, with its abundant pores and functional groups, directly faces the external environment, enabling rapid capture and adsorption of heavy metal ions from the soil solution. Ions penetrating the shell enter the inner resin layer, where they are further immobilized by ion exchange of sulfonic acid groups and coordination adsorption of iron, cerium, and zinc metal oxides. This ensures the stability and irreversibility of heavy metal adsorption. Simultaneously, the modified rice husk-based biochar, embedded in the calcium alginate gel network, introduces micropores and channels into the gel, increasing the entry of water into the core resin layer. The lipid channel, calcium alginate gel, acts as a smart water molecule regulating valve. When the soil is moist, it allows water to pass through and be absorbed and stored by the core resin. When the soil is dry, it slows down the outward diffusion of internal water, achieving slow release. This regulates and enhances the water retention performance of the core resin. Furthermore, both biochar and calcium alginate are soil-like organic matter components that can bind tightly with soil particles, avoiding the interfacial voids between pure synthetic resin and soil. The outer shell also buffers the physical compression of plant roots when the resin absorbs water and expands, eliminating the inhibitory effect of pure resin on seedling growth, thus obtaining a soil remediation and drought-resistant material.

[0053] Example 3

[0054] This embodiment proposes a soil remediation and drought-resistant material, comprising the following components in parts by weight: 3 parts modified rice husk-based biochar, 8 parts iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin, 0.3 parts sodium alginate, and 0.5 parts calcium chloride.

[0055] The iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin is made from the following components in parts by weight: 3 parts of double-modified exchange resin, 13.5 parts of iron nitrate nonahydrate, 8.3 parts of cerium nitrate hexahydrate, and 3.6 parts of zinc nitrate hexahydrate.

[0056] The preparation method of modified rice husk-based biochar specifically includes the following steps:

[0057] (1) 90.0g of rice husks were first washed with deionized water, then dried in an oven at 100℃ for 1 hour, pulverized, and sieved with an 80-mesh sieve. The resulting rice husk powder was placed in a covered ceramic crucible, covered, and placed in a muffle furnace at 600℃ for anaerobic carbonization treatment for 2 hours. After natural cooling, it was taken out and washed with deionized water until the filtrate was clear. The washed carbonized rice husk powder was then placed in an oven at 70℃ for 1 hour. The biochar made from rice husks has high silicon content and a porous structure. This porous structure does not It provides a large number of physical adsorption sites for heavy metal ions and can adsorb and store a large amount of water, enhancing the soil's water retention capacity. At the same time, the amorphous silicon and carbonates it contains can dissolve in the soil solution and form silicate or carbonate precipitates with heavy metals, transforming heavy metals from an exchangeable state that is easily absorbed by plants into a stable and non-toxic residue state. Rice husk biochar can release soluble silicon and deposit it in plant epidermal cells to form a silicified cell layer, reducing water loss through transpiration from the cuticle, thus obtaining rice husk-based biochar.

[0058] (2) Dissolve tetrasodium iminodisuccinate in 500mL of deionized water and adjust the pH to 9.0. The amount of tetrasodium iminodisuccinate added is 10.0g. Tetrasodium iminodisuccinate is rich in carboxyl and amino groups, which can effectively complex heavy metal ions. Moreover, tetrasodium iminodisuccinate can maintain excellent chelation stability over a wide pH range, solving the problem of traditional chelating agents failing in high pH environments. Adjust the volume to 600mL to form a tetrasodium iminodisuccinate solution for later use. Then weigh 30.0g of the rice husk-based biochar described in step (1) and add it to the tetrasodium iminodisuccinate solution. Place it in a shaker at room temperature and shake for 20h at a shaking speed of 10. After the reaction was completed at 0 rpm, the mixture was filtered and the filter cake was repeatedly washed with deionized water until the pH of the washing liquid was 7.0 and the conductivity was <50 μS / cm. Then, the washed filter cake was dried in a 70℃ oven for 1 hour. Tetrasodium iminodisuccinate was loaded onto rice husk-based biochar for modification treatment, so that the strong chelating ability of tetrasodium iminodisuccinate combined with the porous structure of rice husk biochar, which greatly improved the stability and passivation ability of heavy metals in the soil, reduced the absorption and accumulation of heavy metals by crops, and the well-developed porous structure of rice husk-based biochar could play a water storage role after being applied to the soil, effectively absorbing and retaining water, reducing evaporation and seepage losses, thus obtaining modified rice husk-based biochar.

[0059] This embodiment provides a method for preparing a soil remediation and drought-resistant material, which specifically includes the following steps:

[0060] S1. 1.6g of hydrogen-containing silicone oil and 6.8g of dichloromethane were poured into nano-silica. The amount of nano-silica used was 20.0g, with a particle size of 30nm. Nano-silica, as rigid particles, constructed a compressive-resistant skeleton, increasing the mechanical strength and structural stability of the resin material. This allowed it to maintain open pores after absorbing water and swelling, preventing it from being flattened under soil load, thus ensuring the durability of the water-holding space. Nano-silica can also serve as a carrier; its nanoscale size and uneven surface defects provide numerous nucleation sites for subsequent metal oxides. The reaction was carried out at 35℃ for 30 minutes. Vacuum drying at 0.090 MPa and 60℃ causes a chemical reaction between silicone oil and the hydroxyl groups on the surface of nano-silica, changing the silica surface from hydrophilic to hydrophobic, thus improving its compatibility with the polymer matrix. The introduction of modified nano-silica can enhance the structural stability of the material and improve its water retention performance by adjusting the crosslinking density and hydrophilic-hydrophobic balance of the polymer. In addition, after adsorbing heavy metals, the rigid silica framework can maintain the basic structure of the material and prevent the chain segment collapse caused by the covering of organic active sites, thereby maintaining the water retention and repair capabilities of the material, resulting in modified nano-silica powder.

[0061] S2. Add 0.3g gelatin, 0.03g hydroxypropyl methylcellulose, and 1.0g sodium chloride to 100mL deionized water and heat to 40℃ to dissolve. Set aside as the aqueous phase. In a beaker, add 6mL styrene and 1mL hydroxyethyl methacrylate sequentially, mix well, then add 6mL divinylbenzene and 5mL n-heptane, and stir for 10min. Then add 5.0g of the modified nano-silica powder described in step S1, and sonicate for 5min. Finally, add 0.1g benzoyl peroxide and stir for 5min to obtain the oil phase. Set aside as the oil phase. While stirring at 250rpm, slowly add the oil phase dropwise to the aqueous phase at a rate of 1mL / min. Heat to 80℃, maintain the temperature and stir for 3h, filter, wash the solid product three times with deionized water, and dry. Modified nano-silica powder, as a rigid filler, is uniformly dispersed in a polymer network, forming a spherical structure with high cross-linking degree, hierarchical pore structure, and rich in hydroxyl functional groups. This hybrid resin material adsorbs exchangeable heavy metals in the soil solution into the resin through multiple adsorption mechanisms such as chemical complexation, physical adsorption, and cation exchange, effectively reducing their migration. At the same time, the porous structure of the resin can store water, and hydrophilic groups such as hydroxyl groups enhance water affinity. Both of these factors improve drought resistance. The spherical shape helps to improve soil aggregate structure, increase porosity, and reduce water evaporation. In addition, the modified nano-silica powder can prevent polymer chain collapse after water absorption, ensuring continuous exposure of adsorption sites and further maintaining the adsorption and water retention functions of the material, resulting in resin white spheres.

[0062] S3. Weigh 6.0g of the resin white balls described in step S2 and place them in a 250mL three-necked flask. Add 8mL of a mixed solvent of dichloromethane and 2mL of 1,2-dichloroethane. Allow the mixture to swell at room temperature for 10 minutes. Under ice-water bath cooling, slowly add a 90% sulfuric acid solution, controlling the system temperature to not exceed 30℃ during the addition process. The amount of 90% sulfuric acid solution added is 50mL. When the sulfuric acid solution acts on the styrene-divinylbenzene copolymer under heating conditions, it can introduce sulfonic acid groups onto the benzene ring. Sulfonic acid groups not only provide... The addition of exchange sites allows for the formation of continuous ion exchange regions within the resin, ensuring rapid diffusion and exchange of heavy metal ions. Simultaneously, the sulfonic acid groups, as strong hydrophilic groups, significantly enhance the resin's water absorption. After the addition is complete, the mixture is stirred at room temperature for 1 hour, then heated to 60°C for another hour, and finally to 80°C for 2 hours. After the reaction, it is allowed to cool naturally to room temperature, then stirred openly in a fume hood for 50 minutes to confirm complete dichloromethane evaporation. The mixture is then placed in an ice-water bath, and 40 mL of a 50% sulfuric acid solution is slowly added, maintaining the system temperature below 35°C. Pour off the acid solution and place the resin in saturated saline solution at 0°C. Wash with deionized water until the pH is neutral. Then transfer the resin to a beaker and add 80 mL of 5% (w / w) dilute nitric acid solution. The dilute nitric acid can oxidize the sulfonated resin, and the introduced phenolic hydroxyl groups provide additional complexing sites to form stable chelates with heavy metals, improving immobilization efficiency. The introduced nitro groups enhance the polarity and hydrophilicity of the resin, improving water wetting and transfer. Stir the reaction in a 50°C water bath for 0.5 h, pour off the acid solution, and wash repeatedly with deionized water until the pH is neutral. Neutral, the oxidized and washed resin balls are transferred into the adsorption column and washed sequentially with 5% sodium hydroxide solution, deionized water, 5% sulfuric acid solution, and deionized water. After repeating the operation three times, the resin balls are filtered and dried. The double-modified ion exchange resin prepared by this process is a strong acid cation exchange resin. Through sulfonation and oxidation, sulfonic acid groups and oxygen-containing functional groups are introduced, while the porous structure and water retention function of the original resin balls are retained. This allows it to effectively fix heavy metals under drought conditions and reduce the migration of heavy metals, thus obtaining the double-modified ion exchange resin.

[0063] S4. Add ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate sequentially to 100 mL of deionized water. The amounts of ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate added are 13.5 g, 8.3 g, and 3.6 g, respectively. The oxides of iron, cerium, and zinc have a large number of surface hydroxyl groups, which can form stable complexes or surface precipitates with heavy metal ions, significantly reducing the desorption rate of heavy metals, achieving true passivation and fixation, and preventing secondary pollution. The iron, cerium, and zinc oxides act as strong adsorption sites, protecting the hydrophilic groups such as hydroxyl and sulfonic acid groups on the polymer backbone from being occupied by heavy metals, ensuring the long-term maintenance of the material's water-holding capacity. A composite nitrate solution is obtained for later use. Weigh 3.0 g of the double-modified exchange resin described in step S3 and immerse it in the composite nitrate solution. In an acid salt solution, the mixture was placed on a shaker at 100 rpm for 1 hour at room temperature. After filtration, the solid was collected and immersed in 100 mL of 5% sodium hydroxide solution. The mixture was then reacted in a water bath at 40°C for 4 hours. After filtration, the solid product was washed with deionized water until the pH of the eluent was neutral. It was then dried at 60°C and heat-treated at 200°C for 1 hour. Iron-cerium-zinc ternary metal oxide nanoparticles were firmly loaded on the inner surface of the pores of the double-modified exchange resin. This ternary metal oxide has more lattice defects and active sites, providing strong coordination adsorption function. It exhibits a strong affinity for various heavy metal cations such as cadmium, lead, copper, and zinc, as well as oxygen-containing anions in the soil, effectively reducing the migration of heavy metals. This yields an iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin.

[0064] S5. Weigh 8.0g of the iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin described in step S4, immerse it in 50mL of anhydrous ethanol to swell for 10min, filter, and quickly rinse once with deionized water to obtain pretreated resin. Add 0.3g of sodium alginate to 50mL of 60℃ hot water, stir until completely dissolved, cool to room temperature, add 3.0g of modified rice husk-based biochar, and ultrasonically disperse for 20min to form a biochar suspension for later use. Then add the pretreated resin to the biochar suspension, place it on a shaker, and shake at room temperature for 2h at a shaking speed of 100rpm. The solid material was collected by filtration and immersed in 50 mL of 1% calcium chloride solution. The mixture was stirred at 30 rpm for 40 min, filtered, and the product was washed twice with deionized water. It was then dried at 40℃ for 8 h and then at 60℃ for 4 h. The product was pulverized and sieved through a 20-mesh screen. The modified rice husk-based biochar was uniformly dispersed and embedded in the cross-linked calcium alginate three-dimensional gel network as an outer shell layer. This outer shell layer encapsulated and cross-linked with an iron-cerium-zinc ternary metal oxide-supported composite water-retaining and adsorbing resin, strengthening the interfacial bonding and connection. The iron-cerium-zinc ternary metal oxide-supported composite water-retaining and adsorbing resin served as the core layer. This material not only possesses high water absorption and chemical adsorption sites but also provides sufficient mechanical strength to prevent breakage under external forces. The outer shell, with its abundant pores and functional groups, directly faces the external environment, enabling rapid capture and adsorption of heavy metal ions from the soil solution. Ions penetrating the shell enter the inner resin layer, where they are further immobilized by ion exchange with sulfonic acid groups and coordination adsorption of iron, cerium, and zinc metal oxides. This ensures the stability and irreversibility of heavy metal adsorption. Simultaneously, the modified rice husk-based biochar, embedded in the calcium alginate gel network, introduces micropores and channels into the gel, increasing the entry of water into the core resin. The calcium alginate gel acts as a smart water molecule regulating valve, allowing water to pass through and be absorbed and stored by the core resin when the soil is moist, and slowing down the outward diffusion of internal water when the soil is dry, thus achieving slow release. This regulates and enhances the water retention performance of the core resin. Furthermore, both biochar and calcium alginate are soil-like organic matter components that can bind tightly with soil particles, avoiding the interfacial voids between pure synthetic resin and soil. The outer shell also buffers the physical compression of plant roots when the resin absorbs water and expands, eliminating the inhibitory effect of pure resin on seedling growth, resulting in a soil remediation and drought-resistant material.

[0065] Example 4

[0066] This embodiment proposes a soil remediation and drought-resistant material, comprising the following components in parts by weight: 3 parts modified rice husk-based biochar, 10 parts iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin, 0.5 parts sodium alginate, and 1.0 part calcium chloride.

[0067] The iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin is made from the following components in parts by weight: 5 parts of double-modified exchange resin, 13.5 parts of iron nitrate nonahydrate, 8.3 parts of cerium nitrate hexahydrate, and 3.6 parts of zinc nitrate hexahydrate.

[0068] The preparation method of modified rice husk-based biochar specifically includes the following steps:

[0069] (1) 100.0g of rice husks were first washed with deionized water, then dried in an oven at 100℃ for 1h, pulverized, and sieved with a mesh size of 100 mesh. The resulting rice husk powder was placed in a covered ceramic crucible, covered, and placed in a muffle furnace at 600℃ for anaerobic carbonization treatment for 2h. After natural cooling, it was taken out and washed with deionized water until the filtrate was clear. The washed carbonized rice husk powder was placed in an oven at 70℃ for 1h. The biochar made from rice husks has high silicon content and porous structure. This porous structure Not only does it provide a large number of physical adsorption sites for heavy metal ions, but it can also adsorb and store a large amount of water, enhancing the soil's water retention capacity. At the same time, the amorphous silicon and carbonates it contains can dissolve in the soil solution and form silicate or carbonate precipitates with heavy metals, transforming heavy metals from an exchangeable state that is easily absorbed by plants into a stable, non-toxic residue state. Rice husk biochar can release soluble silicon and deposit it in plant epidermal cells, forming a silicified cell layer, reducing water loss through transpiration from the cuticle, thus obtaining rice husk-based biochar.

[0070] (2) Dissolve tetrasodium iminodisuccinate in 500mL of deionized water and adjust the pH to 9.0. The amount of tetrasodium iminodisuccinate added is 10.0g. Tetrasodium iminodisuccinate is rich in carboxyl and amino groups, which can effectively complex heavy metal ions. Moreover, tetrasodium iminodisuccinate can maintain excellent chelation stability over a wide pH range, solving the problem of traditional chelating agents failing in high pH environments. Adjust the volume to 600mL to form a tetrasodium iminodisuccinate solution for later use. Then weigh 30.0g of the rice husk-based biochar described in step (1) and add it to the tetrasodium iminodisuccinate solution. Place it in a shaker at room temperature and shake for 20h at a shaking speed of 15. After the reaction was completed at 0 rpm, the mixture was filtered and the filter cake was repeatedly washed with deionized water until the pH of the washing liquid was 7.0 and the conductivity was <50 μS / cm. Then, the washed filter cake was dried in a 70℃ oven for 1 hour. Tetrasodium iminodisuccinate was loaded onto rice husk-based biochar for modification treatment, so that the strong chelating ability of tetrasodium iminodisuccinate combined with the porous structure of rice husk biochar, which greatly improved the stability and passivation ability of heavy metals in the soil, reduced the absorption and accumulation of heavy metals by crops, and the well-developed porous structure of rice husk-based biochar could play a water storage role after being applied to the soil, effectively absorbing and retaining water, reducing evaporation and seepage losses, thus obtaining modified rice husk-based biochar.

[0071] This embodiment provides a method for preparing a soil remediation and drought-resistant material, which specifically includes the following steps:

[0072] S1. 1.8g of hydrogen-containing silicone oil and 7.2g of dichloromethane were poured into nano-silica. The amount of nano-silica used was 20.0g, with a particle size of 30nm. Nano-silica, as rigid particles, constructed a compressive-resistant skeleton, increasing the mechanical strength and structural stability of the resin material. This allowed it to maintain open pores after absorbing water and swelling, preventing it from being flattened under soil load, thus ensuring the durability of the water-holding space. Nano-silica can also serve as a carrier; its nanoscale size and uneven surface defects provide numerous nucleation sites for subsequent metal oxides. The reaction was heated at 35℃ for 30 minutes. Vacuum drying at 0.095 MPa and 60℃ causes a chemical reaction between silicone oil and the hydroxyl groups on the surface of nano-silica, changing the silica surface from hydrophilic to hydrophobic and improving its compatibility with the polymer matrix. The introduction of modified nano-silica can enhance the structural stability of the material and improve its water retention performance by adjusting the crosslinking density and hydrophilic-hydrophobic balance of the polymer. In addition, after adsorbing heavy metals, the rigid silica framework can maintain the basic structure of the material and prevent the chain segment collapse caused by the covering of organic active sites, thereby maintaining the water retention and repair capabilities of the material, resulting in modified nano-silica powder.

[0073] S2. Add 0.5g gelatin, 0.05g hydroxypropyl methylcellulose, and 1.5g sodium chloride to 100mL deionized water and heat to 50℃ to dissolve. Set aside as the aqueous phase. In a beaker, add 8mL styrene and 2mL hydroxyethyl methacrylate sequentially, mix well, then add 8mL divinylbenzene and 8mL n-heptane, and stir for 10min. Then add 5.0g of the modified nano-silica powder described in step S1, and sonicate for 5min. Finally, add 0.2g benzoyl peroxide and stir for 5min to obtain the oil phase. Set aside as the oil phase. While stirring at 250rpm, slowly add the oil phase dropwise to the aqueous phase at a rate of 1mL / min. Heat to 80℃, maintain the temperature and stir for 3h, filter, wash the solid product three times with deionized water, and dry. Modified nano-silica powder, as a rigid filler, is uniformly dispersed in a polymer network, forming a spherical structure with high cross-linking degree, hierarchical pore structure, and rich in hydroxyl functional groups. This hybrid resin material adsorbs exchangeable heavy metals in the soil solution into the resin through multiple adsorption mechanisms such as chemical complexation, physical adsorption, and cation exchange, effectively reducing their migration. At the same time, the porous structure of the resin can store water, and hydrophilic groups such as hydroxyl groups enhance water affinity. Both of these factors improve drought resistance. The spherical shape helps to improve soil aggregate structure, increase porosity, and reduce water evaporation. In addition, the modified nano-silica powder can prevent polymer chain collapse after water absorption, ensuring continuous exposure of adsorption sites and further maintaining the adsorption and water retention functions of the material, resulting in resin white spheres.

[0074] S3. Weigh 8.0g of the resin white balls described in step S2 and place them in a 250mL three-necked flask. Add 8mL of a mixed solvent of dichloromethane and 2mL of 1,2-dichloroethane. Allow the mixture to swell at room temperature for 10 minutes. While cooling in an ice-water bath, slowly add a 90% sulfuric acid solution, controlling the system temperature to not exceed 30℃ during the addition process. The amount of 90% sulfuric acid solution added is 50mL. When the sulfuric acid solution acts on the styrene-divinylbenzene copolymer under heating conditions, it can introduce sulfonic acid groups onto the benzene ring. Sulfonic acid groups not only provide... The addition of exchange sites allows for the formation of continuous ion exchange regions within the resin, ensuring rapid diffusion and exchange of heavy metal ions. Simultaneously, the sulfonic acid groups, as strong hydrophilic groups, significantly enhance the resin's water absorption. After the addition is complete, the mixture is stirred at room temperature for 1 hour, then heated to 60°C for another hour, and finally to 80°C for 2 hours. After the reaction, it is allowed to cool naturally to room temperature, then stirred openly in a fume hood for 50 minutes to confirm complete dichloromethane evaporation. The mixture is then placed in an ice-water bath, and 40 mL of a 50% sulfuric acid solution is slowly added, maintaining the system temperature below 35°C. Pour off the acid solution and place the resin in saturated saline solution at 0°C. Wash with deionized water until the pH is neutral. Then transfer the resin to a beaker and add 80 mL of 5% (w / w) dilute nitric acid solution. The dilute nitric acid can oxidize the sulfonated resin, and the introduced phenolic hydroxyl groups provide additional complexing sites to form stable chelates with heavy metals, improving immobilization efficiency. The introduced nitro groups enhance the polarity and hydrophilicity of the resin, improving water wetting and transfer. Stir the reaction in a 50°C water bath for 0.5 h, pour off the acid solution, and wash repeatedly with deionized water until the pH is neutral. Neutral, the oxidized and washed resin balls are transferred into the adsorption column and washed sequentially with 5% sodium hydroxide solution, deionized water, 5% sulfuric acid solution, and deionized water. After repeating the operation three times, the resin balls are filtered and dried. The double-modified ion exchange resin prepared by this process is a strong acid cation exchange resin. Through sulfonation and oxidation, sulfonic acid groups and oxygen-containing functional groups are introduced, while the porous structure and water retention function of the original resin balls are retained. This allows it to effectively fix heavy metals under drought conditions and reduce the migration of heavy metals, thus obtaining the double-modified ion exchange resin.

[0075] S4. Add ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate sequentially to 100 mL of deionized water. The amounts of ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate added are 13.5 g, 8.3 g, and 3.6 g, respectively. The oxides of iron, cerium, and zinc have a large number of surface hydroxyl groups, which can form stable complexes or surface precipitates with heavy metal ions, significantly reducing the desorption rate of heavy metals, achieving true passivation and fixation, and preventing secondary pollution. The iron, cerium, and zinc oxides act as strong adsorption sites, protecting the hydrophilic groups such as hydroxyl and sulfonic acid groups on the polymer backbone from being occupied by heavy metals, ensuring the long-term maintenance of the material's water-holding capacity. A composite nitrate solution is obtained for later use. Weigh 5.0 g of the double-modified exchange resin described in step S3 and immerse it in the composite nitrate solution. In an acid salt solution, the mixture was placed on a shaker at 100 rpm for 1 hour at room temperature. After filtration, the solid was collected and immersed in 100 mL of 5% sodium hydroxide solution. The mixture was then reacted in a water bath at 40°C for 4 hours. After filtration, the solid product was washed with deionized water until the pH of the eluent was neutral. It was then dried at 60°C and heat-treated at 200°C for 1 hour. Iron-cerium-zinc ternary metal oxide nanoparticles were firmly loaded on the inner surface of the pores of the double-modified exchange resin. This ternary metal oxide has more lattice defects and active sites, providing strong coordination adsorption function. It exhibits a strong affinity for various heavy metal cations such as cadmium, lead, copper, and zinc, as well as oxygen-containing anions in the soil, effectively reducing the migration of heavy metals. This yields an iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin.

[0076] S5. Weigh 10.0g of the iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin described in step S4, immerse it in 50mL of anhydrous ethanol to swell for 10min, filter, and quickly rinse once with deionized water to obtain pretreated resin. Add 0.5g of sodium alginate to 50mL of 70℃ hot water, stir until completely dissolved, cool to room temperature, add 3.0g of modified rice husk-based biochar, and ultrasonically disperse for 20min to form a biochar suspension for later use. Then add the pretreated resin to the biochar suspension, place it on a shaker, and shake at room temperature for 2h at a shaking speed of 200rpm. The solid material was collected by filtration and immersed in 50 mL of 2% calcium chloride solution. The mixture was stirred at 30 rpm for 40 min, filtered, and the product was washed twice with deionized water. It was then dried at 40℃ for 8 h and then at 60℃ for 4 h. The product was pulverized and sieved through a 40-mesh screen. The modified rice husk-based biochar was uniformly dispersed and embedded in the cross-linked calcium alginate three-dimensional gel network as an outer shell layer. This outer shell layer encapsulated and cross-linked with an iron-cerium-zinc ternary metal oxide-supported composite water-retaining and adsorbing resin, strengthening the interfacial bonding and connection. The iron-cerium-zinc ternary metal oxide-supported composite water-retaining and adsorbing resin served as the core layer. This material not only possesses high water absorption and chemical adsorption sites but also provides sufficient mechanical strength to prevent breakage under external forces. The outer shell, with its abundant pores and functional groups, directly faces the external environment, enabling rapid capture and adsorption of heavy metal ions from the soil solution. Ions penetrating the shell enter the inner resin layer, where they are further immobilized by ion exchange with sulfonic acid groups and coordination adsorption of iron, cerium, and zinc metal oxides. This ensures the stability and irreversibility of heavy metal adsorption. Simultaneously, the modified rice husk-based biochar, embedded in the calcium alginate gel network, introduces micropores and channels into the gel, increasing the entry of water into the core resin. The calcium alginate gel acts as a smart water molecule regulating valve, allowing water to pass through and be absorbed and stored by the core resin when the soil is moist, and slowing down the outward diffusion of internal water when the soil is dry, thus achieving slow release. This regulates and enhances the water retention performance of the core resin. Furthermore, both biochar and calcium alginate are soil-like organic matter components that can bind tightly with soil particles, avoiding the interfacial voids between pure synthetic resin and soil. The outer shell also buffers the physical compression of plant roots when the resin absorbs water and expands, eliminating the inhibitory effect of pure resin on seedling growth, resulting in a soil remediation and drought-resistant material.

[0077] Comparative Example 1

[0078] This comparative example provides a soil remediation drought-resistant material, which differs from Example 1 in that the modified rice husk-based biochar does not contain tetrasodium iminodisuccinate; the preparation method of the modified rice husk-based biochar does not include step (2); and the preparation method of the soil remediation drought-resistant material is the same as that of Example 1.

[0079] Comparative Example 2

[0080] This comparative example provides a soil remediation and drought-resistant material, which differs from Example 1 in that the iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin does not undergo double modification treatment of the resin white balls; the preparation method of modified rice husk-based biochar is the same as in Example 1; and the preparation method of the soil remediation and drought-resistant material does not include step S3.

[0081] Comparative Example 3

[0082] This comparative example provides a soil remediation and drought-resistant material, which differs from Example 1 in that the iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin does not contain iron nitrate nonahydrate, cerium nitrate hexahydrate, or zinc nitrate hexahydrate; the preparation method of the modified rice husk-based biochar is the same as in Example 1; and the preparation method of the soil remediation and drought-resistant material does not include step S4.

[0083] Experimental Example 1

[0084] Water retention performance test

[0085] Test samples: Soil remediation and drought-resistant materials prepared in Examples 1-4 and Comparative Examples 1-3.

[0086] Test method: This experiment selected Pb 2+ Experiments were conducted on heavy metal pollutants, with 50 mL Pb. 2+ A solution (1000 mg / L lead nitrate) was added to 100 g of soil and matured at 25 °C for 5 days to obtain simulated contaminated soil. Then, 100 g of dried contaminated soil and 0.5 g of test sample were mixed evenly and dispersed in a plastic cup with holes at the bottom (with a layer of weighed filter paper M placed at the bottom). 滤纸 Weigh and record M. 杯 Meanwhile, a plastic cup containing only 100g of dry contaminated soil, without any test sample, was used as a control group. A container holding a 2g / L calcium chloride solution was then nested at the bottom of the plastic cup. The mixture was allowed to stand for 10 hours until saturation. The plastic cup was then removed, transferred to a tray lined with dry filter paper, and allowed to stand for 1 hour. The weight (M) was then measured again. 测试后 Calculate the water holding capacity (%) according to the following formula:

[0087] Water holding capacity of the experimental group = (M 测试后 -M 杯 -M 滤纸 -0.5) / 100;

[0088] Water holding capacity of the control group = (M 测试后 -M 杯 -M 滤纸 ) / 100;

[0089] Water holding capacity (%) = (Water holding capacity of experimental group - Water holding capacity of control group) / Water holding capacity of control group × 100%.

[0090] Figure 1 The figures show the water-holding performance results of Examples 1-4 and Comparative Examples 1-3. As shown, the water-holding performance of Examples 1-4 is 307-350%, indicating strong water-holding performance; the water-holding performance of Comparative Examples 1-3 is 135-265%, indicating average or weak water-holding performance. The modified rice husk-based biochar of Comparative Example 1 does not contain tetrasodium iminodisuccinate, and the core resin still maintains a high water absorption rate, but the wettability and hydrophilicity of the biochar surface decrease, slightly reducing the overall water-holding capacity, resulting in average water-holding performance. The iron-cerium-zinc ternary alloy of Comparative Example 2... In the oxide-supported composite water-retaining adsorbent resin, no double modification treatment is performed on the resin white spheres, resulting in the lack of hydrophilic groups such as sulfonic acid groups, phenolic hydroxyl groups, and nitro groups. It mainly relies on the outer shell calcium alginate and biochar for water retention, leading to weak water retention performance. In Comparative Example 3, the iron-cerium-zinc ternary metal oxide-supported composite water-retaining adsorbent resin does not contain iron nitrate nonahydrate, cerium nitrate hexahydrate, or zinc nitrate hexahydrate. It cannot protect the hydrophilic groups such as hydroxyl and sulfonic acid groups on the polymer backbone from being occupied by heavy metals through iron-cerium-zinc oxide, resulting in general water retention performance.

[0091] Experiment Example 2

[0092] Repair performance experiment

[0093] Test samples: Soil remediation and drought-resistant materials prepared in Examples 1-4 and Comparative Examples 1-3.

[0094] Test method: This experiment selected Pb 2+ Experiments were conducted on heavy metal pollutants, with 50 mL Pb. 2+ A solution (1000 mg / L lead nitrate) was added to 100 g of soil and matured at 25 °C for 5 days to obtain simulated contaminated soil. Then, 100 g of dried contaminated soil and 0.5 g of test sample were uniformly mixed, and 100 mL of deionized water was added. The mixture was placed in a constant-temperature shaker (303 K, 120 rpm) and reacted for 2 days without adding deionized water. The mixture was then filtered through a 0.45 μm organic filter membrane, and an appropriate amount of the filtrate was used to determine the Pb content using the dithizone spectrophotometric method. 2+ The residual concentration of Pb is specifically defined as follows: in an alkaline buffer medium (pH 9.5), the residual concentration of Pb is... 2+ The compound reacts with dithizone to form a red complex. After extraction with carbon tetrachloride, the organic phase is separated, and its absorbance is measured at 520 nm using a UV-Vis spectrophotometer. Pb is then determined according to the dithizone method. 2+ The standard curve fitting equation for concentration-absorbance is A = 0.1986C + 0.0042(R²). 2 =0.9995), thus obtaining the Pb corresponding to the absorbance of the measured solution. 2+ The mass concentration was determined, and the adsorption capacity (mg / g) of Pb²⁺ was calculated using the following formula:

[0095] Adsorption capacity (mg / g) = (C0 - C) e )×V / m

[0096] Where C0 is the initial pollutant mass concentration in mg / L, C e V represents the mass concentration of the pollutant after adsorption (mg / L), V is the solution volume (L), and m is the amount of test sample added (g).

[0097] Figure 2 The graph shows the adsorption results for Examples 1-4 and Comparative Examples 1-3. As shown, the adsorption capacity of Examples 1-4 was 82-96 mg / g, indicating a good remediation effect. The adsorption capacity of Comparative Examples 1-3 was 28-65 mg / g, indicating a moderate or poor remediation effect. The modified rice husk-based biochar of Comparative Example 1 did not contain tetrasodium iminodisuccinate, and therefore could not stably fix heavy metals to the biochar surface through the chelation effect of tetrasodium iminodisuccinate, reducing the adsorption capacity and resulting in a moderate remediation effect. The iron-cerium-zinc ternary metal oxide of Comparative Example 2... The supported composite water-retaining adsorption resin does not undergo dual modification treatment of the resin white spheres, thus lacking functional groups such as sulfonic acid groups, phenolic hydroxyl groups, and nitro groups that possess heavy metal ion exchange and complexation capabilities. The resin white spheres only provide physical adsorption, resulting in poor remediation effects. The iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin in Comparative Example 3 does not contain iron nitrate nonahydrate, cerium nitrate hexahydrate, or zinc nitrate hexahydrate. The absence of iron-cerium-zinc oxides reduces the coordination and fixation capacity for heavy metals, thereby reducing the adsorption capacity and resulting in mediocre remediation effects.

[0098] The above experimental results show that the water-holding performance and repair effect of Examples 1-4 of the present invention are significantly better than those of Comparative Examples 1-3. Among them, Example 1, which uses modified rice husk-based biochar and iron-cerium-zinc ternary metal oxide supported composite water-holding adsorption resin, has better water-holding performance and repair effect. The modified rice husk-based biochar is uniformly dispersed and embedded in the calcium alginate three-dimensional gel network to form an outer shell layer, which encapsulates and crosslinks the core layer of iron-cerium-zinc ternary metal oxide supported composite water-holding adsorption resin, strengthening the interfacial bonding and connection, and constructing a fast-responding and deeply fixed dual adsorption barrier, ensuring the high efficiency and stability of heavy metal particle repair. In addition, the outer shell layer not only participates in repair but also acts as an intelligent water molecule regulating valve, which plays a role in regulating and enhancing the water-holding performance of the core resin, further reducing the migration of heavy metal particles when water is scarce, and deepening the repair effect.

[0099] 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.

[0100] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A soil remediation and drought-resistant material, characterized in that: The soil remediation and drought-resistant material comprises the following components in parts by weight: 3-5 parts modified rice husk-based biochar, 8-10 parts iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin, 0.3-0.5 parts sodium alginate, and 0.5-1.0 parts calcium chloride; the iron-cerium-zinc ternary metal oxide supported composite water-retaining and adsorbing resin is made from the following components in parts by weight: 3-5 parts double-modified exchange resin, 13.5-14.5 parts iron nitrate nonahydrate, 8.3-9.3 parts cerium nitrate hexahydrate, and 3.6-4.6 parts zinc nitrate hexahydrate.

2. A method for preparing the soil remediation and drought-resistant material according to claim 1, characterized in that: Specifically, the following steps are included: S1. Add 1.6-1.8g of hydrogen-containing silicone oil and 6.8-7.2g of dichloromethane to nano-silica, heat at 35℃ for 30-50min, and vacuum dry at 0.090-0.095MPa and 60℃ to obtain modified nano-silica powder. S2. Add 0.3-0.5g gelatin, 0.03-0.05g hydroxypropyl methylcellulose and 1.0-1.5g sodium chloride to 100mL deionized water and heat to 40-50℃ to dissolve. Set aside as the aqueous phase. In a beaker, add 6-8mL styrene and 1-2mL hydroxyethyl methacrylate in sequence. After mixing evenly, add 6-8mL divinylbenzene and 5-8mL n-heptane and stir for 10-20min. Then add 5.0-6.0g of the modified nano silica powder described in step S1 and sonicate for 5-10min. Finally, add 0.1-0.2g benzoyl peroxide and stir for 5-10min to obtain the oil phase. Set aside as the oil phase. Under stirring at 250rpm, slowly add the oil phase dropwise to the aqueous phase at a rate of 1mL / min. Heat to 80℃ and keep stirring for 3-4h. Filter, wash the solid product three times with deionized water, and dry to obtain resin white balls. S3. Weigh 6.0-8.0g of the resin white balls described in step S2 and place them in a 250mL three-necked flask. Add 8mL of a mixed solvent of dichloromethane and 2mL of 1,2-dichloroethane. Allow the mixture to swell at room temperature for 10-20 minutes. While cooling in an ice-water bath, slowly add a 90% sulfuric acid solution, controlling the system temperature to not exceed 30℃ during the addition process. After the addition is complete, stir the mixture at room temperature for 1-2 hours, then raise the temperature to 60℃ and react for 1-2 hours. Finally, raise the temperature to 80℃ and react for 2-3 hours. After the reaction is complete, allow it to cool naturally to room temperature. Stir the mixture in a fume hood for 50-60 minutes to ensure complete evaporation of the dichloromethane. Then place the mixture in an ice-water bath and slowly stir again. Slowly add 40 mL of 50% sulfuric acid solution, keeping the system temperature below 35°C. Pour off the acid solution and place the resin in saturated saline solution at 0°C. Wash with deionized water until the pH is neutral. Then transfer the resin to a beaker and add 5% dilute nitric acid solution. Stir and react in a 50°C water bath for 0.5-1 h. Pour off the acid solution and wash repeatedly with deionized water until the pH is neutral. Transfer the oxidized and washed resin balls into an adsorption column and wash them sequentially with 5% sodium hydroxide solution, deionized water, 5% sulfuric acid solution, and deionized water. Repeat this process three times. Filter and dry to obtain the double-modified exchange resin. S4. Add ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate sequentially to 100 mL of deionized water to obtain a composite nitrate solution for later use. Weigh 3.0-5.0 g of the double-modified exchange resin described in step S3 and immerse it in the composite nitrate solution. Place it on a shaker at room temperature and shake at 100 rpm for 1-2 hours. Filter, collect the solid, and immerse it in 100 mL of 5% sodium hydroxide solution. React in a water bath at 40°C for 4-6 hours. Filter, wash the solid product with deionized water until the pH of the eluent is neutral, dry it at 60°C, and then heat-treat it at 200°C for 1-2 hours to obtain an iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin. S5. Weigh 8.0-10.0g of the iron-cerium-zinc ternary metal oxide supported composite water-retaining adsorption resin described in step S4, immerse it in 50mL of anhydrous ethanol to swell for 10min, filter, and quickly rinse once with deionized water to obtain pretreated resin. Add 0.3-0.5g of sodium alginate to 50mL of 60-70℃ hot water, stir until completely dissolved, cool to room temperature, add 3.0-5.0g of modified rice husk-based biochar, and ultrasonically disperse for 20-30min to form a biochar suspension. The pretreated resin was then added to the biochar suspension and placed on a shaker. The mixture was shaken at room temperature for 2-4 hours at a shaking speed of 100-200 rpm. After filtration, the solid material was collected and immersed in 50 mL of a 1-2% calcium chloride solution. The mixture was stirred at 30 rpm for 40-50 minutes, filtered, and the product was washed twice with deionized water. It was then dried at 40℃ for 8-10 hours and then at 60℃ for 4-6 hours. The product was then pulverized and sieved with a mesh size of 20-40 to obtain the soil remediation drought-resistant material.

3. The method for preparing soil remediation and drought-resistant materials according to claim 2, characterized in that: In step S1, the amount of nano-silica used is 20.0-24.0g, and the particle size is 30nm.

4. The method for preparing the soil remediation and drought-resistant material according to claim 3, characterized in that: In step S3, the amount of 90% sulfuric acid solution added is 50-60 mL; the amount of dilute nitric acid solution added is 80-100 mL.

5. The method for preparing the soil remediation and drought-resistant material according to claim 4, characterized in that: In step S4, the amounts of ferric nitrate nonahydrate, cerium nitrate hexahydrate, and zinc nitrate hexahydrate added are 13.5-14.5g, 8.3-9.3g, and 3.6-4.6g, respectively.

6. The method for preparing the soil remediation and drought-resistant material according to claim 5, characterized in that: The preparation method of the modified rice husk-based biochar specifically includes the following steps: (1) Wash 90.0-100.0g of rice husks with deionized water, dry them in an oven at 100℃ for 1-2 hours, crush them, and sieve them with a mesh size of 80-100 mesh. Place the rice husk powder in a covered ceramic crucible, cover it, and put it in a muffle furnace at 600℃ for anaerobic carbonization treatment for 2-3 hours. After natural cooling, take it out and wash it with deionized water until the filtrate is clear. Place the washed carbonized rice husk powder in an oven at 70℃ for 1-2 hours to obtain rice husk-based biochar. (2) Dissolve tetrasodium iminodisuccinate in 500mL of deionized water and adjust the pH to 9.

0. Make up the volume to 600mL to form a tetrasodium iminodisuccinate solution for later use. Then weigh 30.0-40.0g of the rice husk-based biochar described in step (1) and add it to the tetrasodium iminodisuccinate solution. Place it in a shaker at room temperature and shake for 20-24h at a shaking speed of 100-150rpm. After the reaction is completed, filter the filter cake repeatedly with deionized water until the pH of the washing liquid is 7.0 and the conductivity is <50μS / cm. Then place the washed filter cake in a 70℃ oven and dry for 1-2h to obtain modified rice husk-based biochar.

7. The method for preparing soil remediation and drought-resistant materials according to claim 6, characterized in that: In step (2), the amount of tetrasodium iminodisuccinate added is 10.0g.

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