Adsorbent for soil heavy metal remediation and preparation method and application thereof
By developing an adsorbent composed of karizo rice extract, biochar and sodium alginate, the problems of plant heavy metal enrichment and reduced symbiosis efficiency of arbuscular mycorrhizal fungi in soil heavy metal pollution repair are solved, efficient heavy metal adsorption and passivation are achieved, and the growth of arbuscular mycorrhizal fungi and rice infection rate are promoted, ensuring the safety and sustainability of agricultural production.
Patent Information
- Application Number
- CN202411824729.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-12
- Publication Date
- 2025-03-18
AI Technical Summary
When the prior art uses biochar and arbuscular mycorrhizal fungi to repair soil heavy metal pollution, it is difficult to avoid plant heavy metal enrichment and reduced symbiosis efficiency of arbuscular mycorrhizal fungi, resulting in threatening the safety and sustainability of agricultural production.
An adsorbent is developed, consisting of cherry rice extract, biochar and sodium alginate. It is dispersed in a polyethyleneimine solution by preparation method and dripped into a calcium chloride solution for soil heavy metal repair, while improving the activity of arbuscular mycorrhizal fungi and the infection rate of rice.
This adsorbent significantly improves the adsorption capacity of heavy metals in the soil, reduces the bioavailability of heavy metals, promotes the growth and infection rate of arbuscular mycorrhizal fungi, reduces the heavy metal content in rice grains, and ensures the safety and sustainability of agricultural production.
Smart Images
Figure CN119633772A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of soil heavy metal remediation, and relates to an adsorbent for soil heavy metal remediation, and a preparation method and application thereof. Background Art
[0002] Heavy metals such as cadmium (Cd), lead (Pb), chromium (Cr), etc., due to their non-degradability and bioaccumulation, pose a serious threat to soil ecosystems and crop safety. Once these heavy metals enter the soil, they not only affect the structure and function of the soil, but may also accumulate in the human body through the food chain, endangering human health. In order to alleviate soil heavy metal pollution, various remediation technologies have emerged. Among them, the application of biochar has attracted much attention because of its ability to adsorb and fix heavy metals in the soil and improve the physical and chemical properties of the soil. Biochar, as a carbon-rich solid substance produced by high-temperature pyrolysis of biomass under anaerobic or hypoxic conditions, has a large specific surface area and rich pore structure, and has good adsorption capacity for heavy metal ions. It is regarded as a promising soil heavy metal pollution remediation material. Although biochar remediation of heavy metal contaminated soil can reduce the enrichment of heavy metals in plants, it often fails to meet the standards of safe production.
[0003] On the other hand, arbuscular mycorrhizal fungi (AMF), as a type of soil microorganism widely present in nature, can form a symbiotic relationship with a variety of plants, significantly promoting plant growth by enhancing plant absorption of water and nutrients and improving plant stress resistance. In agricultural crops such as rice that can coexist with arbuscular mycorrhizal fungi, the infection of arbuscular mycorrhizal fungi can not only increase crop yield and quality, but also alleviate the toxic effects of soil heavy metals on plants to a certain extent. However, when the soil is contaminated by heavy metals, the infection rate and symbiotic efficiency of arbuscular mycorrhizal fungi will be significantly reduced, which does not weaken its positive effect on plants, making it difficult to use in soils contaminated by heavy metals.
[0004] At present, the use of biochar and arbuscular mycorrhizal fungi technology to repair soil heavy metal pollution and promote agricultural production faces the dual challenges of biochar possibly aggravating plant heavy metal enrichment and heavy metal pollution reducing the efficiency of arbuscular mycorrhizal fungi symbiosis. Therefore, it is urgent to develop a comprehensive technical strategy that can effectively repair soil heavy metal pollution, avoid excessive enrichment of heavy metals in plants, and ensure the sustainability and safety of agricultural production. Summary of the invention
[0005] In order to overcome the above technical problems, the present invention has developed an adsorbent for soil heavy metal remediation and its preparation method and application. The adsorbent provided by the present invention can achieve soil heavy metal remediation while being beneficial to improving AMF activity and mycelium growth, increasing the infection rate of AMF to rice, and reducing the heavy metal content in rice grains.
[0006] In one aspect, the present invention relates to a method for preparing an adsorbent for soil heavy metal remediation, comprising: grinding kudzu vine with liquid nitrogen and then extracting with an organic solution to obtain a kudzu vine extract;
[0007] Dispersing the kudzu vine extract, biochar and sodium alginate in a polyethyleneimine solution to prepare a core material;
[0008] The core material is dropped into a calcium chloride solution to obtain the adsorbent.
[0009] Furthermore, in the method for preparing an adsorbent for soil heavy metal remediation provided by the present invention, the organic solution is a methanol solution.
[0010] Furthermore, in the preparation method of the adsorbent for soil heavy metal remediation provided by the present invention, every 1g of the powder of the schizonepeta tenuifolia after grinding with liquid nitrogen is mixed with 1-5mL of 80wt% methanol solution, extracted at 0-5°C for 8-16h, and then centrifuged to obtain the supernatant to obtain the schizonepeta tenuifolia extract.
[0011] Furthermore, in the method for preparing an adsorbent for soil heavy metal remediation provided by the present invention, the centrifugal parameter is 10,000 to 15,000 rpm for 5 to 15 min.
[0012] Furthermore, in the preparation method of the adsorbent for soil heavy metal remediation provided by the present invention, every 10g of the Pueraria lobata extract, 10-20g of the biochar and 2-5g of sodium alginate are dispersed in 150mL of 0.05-0.1g / mL polyethyleneimine solution and stirred evenly to obtain the core material.
[0013] Furthermore, in the method for preparing an adsorbent for soil heavy metal remediation provided by the present invention, the concentration of the calcium chloride solution is 0.01 to 0.1 mol / L.
[0014] On the other hand, the present invention relates to an adsorbent for soil heavy metal remediation, which is prepared by the preparation method of the adsorbent for soil heavy metal remediation.
[0015] In another aspect, the present invention relates to an adsorbent for soil heavy metal remediation for passivating heavy metals in soil.
[0016] On the other hand, the present invention relates to the use of an adsorbent for soil heavy metal remediation in rice cultivation.
[0017] Furthermore, in the application provided by the present invention, rice is planted in soil contaminated by heavy metals, arbuscular mycorrhizal fungi are added throughout the growth cycle of the rice, and the adsorbent is applied to the soil.
[0018] The arbuscular mycorrhizal fungi of the present invention are referred to as AMF for short, and the arbuscular mycorrhizal fungi are Rhizophagus irregularis or Glomus mosseae.
[0019] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:
[0020] (1) Highly efficient heavy metal adsorption and passivation capabilities: The adsorbent provided by the present invention combines kudzu vine extract, biochar and sodium alginate, and significantly improves the adsorption capacity of heavy metals (such as arsenic and cadmium) in the soil through synergistic effects, and converts exchangeable heavy metals into bound states, reducing their biological effectiveness. This highly efficient adsorption and passivation capability helps reduce heavy metal pollution to soil and crops and improve soil quality.
[0021] (2) Promote the growth and infection of AMF: While repairing soil heavy metals, the adsorbent of the present invention also significantly increases the infection rate of arbuscular mycorrhizal fungi (AMF) in the rice root system. The enhancement of AMF helps the development of plant roots and the absorption of nutrients, further improving the tolerance of crops to heavy metals and overall growth performance.
[0022] (3) Reducing the heavy metal content in agricultural products: After planting rice with the adsorbent of the present invention, the cadmium content in the rice grains was significantly reduced, far lower than the blank control group and the positive control group using only biochar. This advantage is of great significance for ensuring the safety of agricultural products and reducing the entry of heavy metals into the human body through the food chain. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0024] Figure 1 This is a graph showing the bioavailable concentration and passivation efficiency of arsenic-contaminated soil after treatment with different adsorbents.
[0025] Figure 2This is a field map of heavy metal contaminated soil before improvement.
[0026] Figure 3 This is a field map of the soil after improvement due to heavy metal contamination. DETAILED DESCRIPTION
[0027] The technical scheme of the present invention is described below in conjunction with the examples, but the present invention is not limited to the following examples. The experimental methods and detection methods described in each example are conventional methods unless otherwise specified; the reagents and materials are available on the market unless otherwise specified, and the % in the following examples are all mass percentages unless otherwise specified.
[0028] In the following examples, the AMF used is the existing Rhizophagus irregularis, which includes the culture matrix after propagation, mycorrhizal root segments, spores and mycelium, etc. The propagation method is potted planting, and the symbiotic plant used for propagation of AMF is corn.
[0029] Example 1
[0030] This embodiment provides a process for preparing an adsorbent for soil heavy metal remediation.
[0031] Step 1: After rinsing the kudzu vine with an average particle size of 4-5 mm with sterile water, adding liquid nitrogen and grinding it with a mortar into 80-100 mesh powder. Take 1g of the powder and mix it with 1mL of 80wt% methanol solution, stir and mix, then extract it in a refrigerator at 0-5℃ for 8h. After the extraction, centrifuge it at 10000rpm for 5min, take the supernatant and filter it to obtain the kudzu vine extract.
[0032] Step 2: Dissolve 7.5 g of polyethyleneimine powder in 150 mL of deionized water and stir until uniform to prepare a 0.05 g / mL polyethyleneimine solution.
[0033] Step 3: Prepare 0.01 mol / L calcium chloride solution.
[0034] Step 4: Use rice straw from farmland that is not contaminated by heavy metals as raw material to prepare biochar using a muffle furnace. Cut the straw to an appropriate size, fill it into a ceramic crucible with a lid, seal it, and place it in a muffle furnace for pyrolysis. Raise the pyrolysis temperature at 20°C / min to 350°C and maintain it for 4 hours. After cooling the prepared material to room temperature, grind it through a 1mm sieve and seal it for later use.
[0035] Step 5: Take 10g of Pueraria lobata extract, 10g of biochar and 2g of sodium alginate and put them into the polyethyleneimine solution. After stirring evenly, slowly drip them into the calcium chloride solution, stir for 2h, and stand at room temperature for 4h to obtain the adsorbent.
[0036] Example 2
[0037] This embodiment provides a process for preparing an adsorbent for soil heavy metal remediation.
[0038] Step 1: After rinsing the cultured kudzu seed with an average particle size of 4-5 mm with sterile water, adding liquid nitrogen and grinding it with a mortar into 80-100 mesh powder. Take 1g of the powder and mix it with 2mL of 80wt% methanol solution, stir and mix, then extract it in a refrigerator at 0-5℃ for 12h. After the extraction, centrifuge it at 12000rpm for 10min, take the supernatant and filter it to obtain the kudzu seed extract.
[0039] Step 2: Dissolve 12 g of polyethyleneimine powder in 150 mL of deionized water and stir until uniform to prepare a 0.08 g / mL polyethyleneimine solution.
[0040] Step 3: Prepare 0.05 mol / L calcium chloride solution.
[0041] Step 4: Use rice straw from farmland that is not contaminated by heavy metals as raw material to prepare biochar using a muffle furnace. Cut the straw to an appropriate size, fill it into a ceramic crucible with a lid, seal it, and place it in a muffle furnace for pyrolysis. Raise the pyrolysis temperature at 20°C / min to 350°C and maintain it for 4 hours. After cooling the prepared material to room temperature, grind it through a 1mm sieve and seal it for later use.
[0042] Step 5: Take 10g of Pueraria lobata extract, 15g of biochar and 3g of sodium alginate and put them into the polyethyleneimine solution. After stirring evenly, slowly drip them into the calcium chloride solution, stir for 2h, and stand at room temperature for 4h to obtain the adsorbent.
[0043] Example 3
[0044] This embodiment provides a process for preparing an adsorbent for soil heavy metal remediation.
[0045] Step 1: After rinsing the cultured kudzu seed with an average particle size of 4-5 mm with sterile water, adding liquid nitrogen and grinding it with a mortar into 80-100 mesh powder. Take 1g of the powder and mix it with 5mL of 80wt% methanol solution, stir and mix, then extract it in a refrigerator at 0-5℃ for 16h. After the extraction, centrifuge it at 15000rpm for 15min, take the supernatant and filter it to obtain the kudzu seed extract.
[0046] Step 2: Dissolve 15 g of polyethyleneimine powder in 150 mL of deionized water and stir until uniform to prepare a 0.1 g / mL polyethyleneimine solution.
[0047] Step 3: Prepare 0.1 mol / L calcium chloride solution.
[0048] Step 4: Use rice straw from farmland that is not contaminated by heavy metals as raw material to prepare biochar using a muffle furnace. Cut the straw to an appropriate size, fill it into a ceramic crucible with a lid, seal it, and place it in a muffle furnace for pyrolysis. Raise the pyrolysis temperature at 20°C / min to 350°C and maintain it for 4 hours. After cooling the prepared material to room temperature, grind it through a 1mm sieve and seal it for later use.
[0049] Step 5: Take 10g of Pueraria lobata extract, 20g of biochar and 5g of sodium alginate and put them into the polyethyleneimine solution. After stirring evenly, slowly drip them into the calcium chloride solution, stir for 2h, and stand at room temperature for 4h to obtain the adsorbent.
[0050] Comparative Example 1
[0051] This comparative example is intended to illustrate the function of adding the kudzu vine extract. This comparative example is the same as Example 1, except that the kudzu vine extract is not added.
[0052] Comparative Example 2
[0053] This comparative example is intended to illustrate the function of the material structure constructed by the present invention. This comparative example is the same as Example 1, except that step 5 is: 10g of kudzu vine extract, 10g of biochar and 2g of sodium alginate are put into a polyethyleneimine solution, stirred evenly and then slowly dripped into a calcium chloride solution, stirred for 2h, and allowed to stand at room temperature for 4h. The gel material is taken out and ground to obtain an adsorbent.
[0054] Example 4
[0055] This example tests the adsorption and passivation of arsenic in soil by different adsorbents.
[0056] With no biochar applied as a control, 2% of the adsorbents prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were respectively applied to the arsenic-contaminated (40 mg / kg) soil, and cultured for 150 days at room temperature, maintaining the soil moisture content at 30%, and determining the exchangeable concentration (mg / kg) and bound concentration (mg / kg) of arsenic in the soil, and calculating the passivation efficiency (%). The soil without adsorbent application was used as a blank control group (CK), and the soil with biochar application was used as a positive control group (PC). The test results are as follows: Figure 1 shown.
[0057] Depend on Figure 1 It can be seen that the adsorbents and biochars prepared in Examples 1 to 3 and Comparative Examples 1 to 2 can reduce the content of available As in the soil to varying degrees. The adsorbents prepared in Examples 1 to 3 can convert more exchangeable As into a bound state with low bioavailability than the adsorbents and biochars prepared in Comparative Examples 1 to 2, and have a better passivation effect. Compared with the adsorbents prepared in Examples 1 to 2, Example 3 has a poorer effect on the conversion of available As in the soil into a residual state, and therefore has a weaker passivation effect.
[0058] Example 5
[0059] This example tests the effects of different adsorbents on rice grown in cadmium-contaminated soil.
[0060] The planting matrix used is a low-contaminated farmland soil with a soil cadmium content of 0.60 mg / kg. The test group is inoculated with AMF for bacterial treatment. After adding the bacterial agent, the total spore density of arbuscular mycorrhizal fungi in the matrix is 2000 spores / liter of matrix. Then 3% of the adsorbent or biochar prepared in Examples 1 to 3 and Comparative Examples 1 to 2 is added. The volume of the planting pot is 2L and the volume of the matrix is 1.5L. After the rice is germinated, it is sown in the cultivation matrix and normal water and fertilizer management is performed. The infection rate of AMF in the rice root system and the cadmium content of the rice grains under different treatments are counted, biochar is used as a positive control (PC), normal soil is used as a negative control (NC), and soil without adsorbent is used as a blank control group (CK). The test results are shown in Table 1.
[0061] Table 1: Effects of different adsorbents on rice grown in cadmium-contaminated soil
[0062] Infection rate (%) Cadmium content in rice grains (mg / kg) Example 1 37.6 0.17 Example 2 31.9 0.13 Example 3 33.6 0.11 Comparative Example 1 21.6 0.28 Comparative Example 2 29.7 0.23 PC 15.9 0.44 NC 38.3 - CK 5.1 0.82
[0063] Based on the above test results, the following conclusions can be drawn: First, the adsorbents prepared by Examples 1 to 3 significantly increased the arbuscular mycorrhizal fungi (AMF) infection rate of rice roots in cadmium-contaminated soil, and the infection rate was significantly improved compared with the blank control group (CK) without adsorbent and the positive control group (PC) with only biochar added. This shows that the prepared adsorbent not only has no negative impact on the infection of AMF, but may promote its growth and infection ability, thereby contributing to the absorption of nutrients and heavy metal tolerance by rice roots. Secondly, in terms of reducing the cadmium content in rice grains, the adsorbents of Examples 1 to 3 all showed excellent performance, and the cadmium content in rice grains was significantly lower than that in the blank control group (CK) and the positive control group (PC), and with the increase in the amount of kudzu extract, biochar and sodium alginate used in the preparation of the adsorbent (from Example 1 to Example 3), the cadmium content in rice grains showed a downward trend. This indicates that the prepared adsorbent can effectively adsorb cadmium ions in the soil, reduce their transport and accumulation to rice plants, thereby reducing the cadmium content in rice grains and improving the safety of rice.
[0064] In addition, the results of Comparative Example 1 show that the adsorbent without the addition of the kudzu vine extract is not as effective as the example in promoting AMF infection and reducing the cadmium content of rice grains, indicating that the kudzu vine extract plays a key role in the preparation of the adsorbent. Comparative Example 2 changes the morphology of the adsorbent (grinding and crushing), and it is found that its effect is not as good as the example, which further proves the importance of the adsorbent structure constructed by the present invention to its performance.
[0065] In summary, the adsorbent prepared in this experiment showed excellent performance in promoting AMF infection and reducing the cadmium content in rice grains, and its effect was closely related to the preparation process and composition of the adsorbent. These results not only provide new ideas and methods for the remediation of soil heavy metal pollution, but also provide strong technical support for improving the safety of rice.
[0066] The present invention uses the adsorbent prepared in Example 2 for Figure 2 The soil of the field with heavy heavy metal pollution (mainly cadmium) was improved by applying 80.0 kg / mu once every 6 months for 2 consecutive years. Figure 3 The restored landform is shown.
[0067] As described above, the basic principle, main features and advantages of the present invention are well described. The above embodiments and descriptions are only descriptions of the preferred implementation modes of the present invention, and the present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, various changes and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the protection scope determined by the present invention.
Claims
1. A method for preparing an adsorbent for soil heavy metal remediation, characterized in that: include: Grinding the schisandra chinensis with liquid nitrogen and then extracting with an organic solution to obtain a schisandra chinensis extract; Dispersing the kudzu vine extract, biochar and sodium alginate in a polyethyleneimine solution to prepare a core material; The core material is dropped into a calcium chloride solution to obtain the adsorbent.
2. The method for preparing an adsorbent for soil heavy metal remediation according to claim 1, characterized in that: The organic solution is a methanol solution.
3. The method for preparing an adsorbent for soil heavy metal remediation according to claim 2, characterized in that: Every 1g of powder of kudzu vine ground by liquid nitrogen is mixed with 1-5mL of 80wt% methanol solution, extracted at 0-5℃ for 8-16h, and then centrifuged to obtain the supernatant to obtain the kudzu vine extract.
4. The method for preparing an adsorbent for soil heavy metal remediation according to claim 3, characterized in that: The centrifugal parameters are 10000-15000 rpm for 5-15 min.
5. The method for preparing an adsorbent for soil heavy metal remediation according to claim 1, characterized in that: Every 10g of the Pueraria Mirifica extract, 10-20g of the biochar and 2-5g of sodium alginate are dispersed in 150mL of 0.05-0.1g / mL polyethyleneimine solution and stirred evenly to obtain the core material.
6. The method for preparing an adsorbent for soil heavy metal remediation according to claim 1, characterized in that: The concentration of the calcium chloride solution is 0.01-0.1 mol / L.
7. An adsorbent for soil heavy metal remediation, characterized in that: The adsorbent is prepared by the preparation method of the adsorbent for soil heavy metal remediation according to any one of claims 1 to 6.
8. The adsorbent for soil heavy metal remediation according to claim 7 is used to passivate heavy metals in the soil.
9. Use of the adsorbent for soil heavy metal remediation according to claim 7 in rice cultivation.
10. The use according to claim 9, characterized in that: Rice is planted in soil contaminated with heavy metals, and arbuscular mycorrhizal fungi are added throughout the growth cycle of the rice to apply the adsorbent to the soil.