Cyclodextrin hybrid supramolecular hydrogel as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of environmental restoration, and particularly relates to cyclodextrin hybrid supramolecular hydrogel as well as a preparation method and application thereof. A construction unit of the cyclodextrin hybrid supramolecular hydrogel comprises quaternary ammonium salt modified beta-cyclodextrin and hectorite which interacts with the quaternary ammonium salt modified beta-cyclodextrin in an electrostatic manner; plant hormones are included in a cavity of the quaternary ammonium salt modified beta-cyclodextrin. The cavity of the quaternary ammonium salt modified beta-cyclodextrin can effectively include plant hormones such as indoleacetic acid, and then the supramolecular hydrogel is formed through electrostatic interaction between the hectorite and the quaternary ammonium salt modified beta-cyclodextrin. The supramolecular hydrogel adhesive tape provided by the invention has charges and cavities, can include various plant hormones, has the effects of regulating soil salinity and promoting plant growth, and has a synergistic effect with plants in a saline-alkali soil improvement technology to improve the improvement effect. The hydrogel disclosed by the invention is based on multiple non-covalent interaction, has the advantage of controllably releasing plant hormones, and is cooperated with plant remediation to realize sustainable environmental remediation.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation technology, specifically relating to a cyclodextrin hybrid supramolecular hydrogel, its preparation method, and its application. Background Technology

[0002] Saline-alkali land is a widely distributed type of soil degradation globally, which easily leads to reduced crop yields, ecological fragility, and restricts sustainable agricultural development. Existing remediation technologies, such as applying sulfate-based chemical amendments like gypsum and phosphogypsum, are prone to causing secondary pollution and have long bioremediation cycles; physical measures such as deep plowing, land leveling, breaking up compacted layers, and irrigation and drainage for salt leaching are costly.

[0003] Hydrogels have attracted widespread attention due to their reversible assembly and environmentally friendly properties. However, existing hydrogel products are insufficient in terms of salt resistance, water retention capacity, ion adsorption efficiency and stability, making them difficult to adapt to saline-alkali environments. There is an urgent need to develop hydrogel remediation materials that can efficiently promote plant growth in saline-alkali environments. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a cyclodextrin hybrid supramolecular hydrogel, its preparation method, and its applications. The cyclodextrin hybrid supramolecular hydrogel provided by this invention has high efficiency in remediating saline-alkali soils and good effects in promoting plant growth.

[0005] The present invention provides a cyclodextrin hybrid supramolecular hydrogel, wherein the building units of the cyclodextrin hybrid supramolecular hydrogel include quaternary ammonium salt modified β-cyclodextrin and lithium saponite that interacts electrostatically with the quaternary ammonium salt modified β-cyclodextrin; The quaternary ammonium salt modified β-cyclodextrin contains plant hormones within its cavity.

[0006] Preferably, the mass ratio of the quaternary ammonium salt modified β-cyclodextrin to lithium saponite is (56~168):1.

[0007] Preferably, the plant hormone includes one or more of indoleacetic acid, jasmonic acid, gibberellin, and salicylic acid.

[0008] Preferably, the molar ratio of the quaternary ammonium salt modified β-cyclodextrin to the plant hormone is (1~10):1.

[0009] This invention also provides a method for preparing the cyclodextrin hybrid supramolecular hydrogel described above, comprising the following steps: The stock solution was prepared by encapsulating a mixture of quaternary ammonium salt-modified β-cyclodextrin, plant hormone, and first water. The stock solution, lithium saponite, and second water were mixed to form a gel, resulting in the cyclodextrin hybrid supramolecular hydrogel.

[0010] Preferably, the molar ratio of the quaternary ammonium salt modified β-cyclodextrin to the volume of the first water is 10 mmol:(9~12) mL.

[0011] Preferably, the mass ratio of the lithium saponite to the volume of the stock solution is (1~2) g:(2.5~10) mL.

[0012] Preferably, the gelation process further includes freeze drying, which includes a pre-cooling stage and a drying stage in sequence; the temperature of the pre-cooling stage is not higher than -40°C and the time is 1~1.5h; the temperature of the drying stage is -70~-50°C and the time is 48~72h.

[0013] This invention also provides the application of the cyclodextrin hybrid supramolecular hydrogel described in the above technical solution or the cyclodextrin hybrid supramolecular hydrogel obtained by the above preparation method in saline-alkali soil.

[0014] Preferably, the application includes the following steps: The cyclodextrin-hybridized supramolecular hydrogel was added to saline-alkali soil, and then plants were transplanted into the resulting mixed soil for cultivation, thereby restoring the saline-alkali soil. Preferably, the amount of the cyclodextrin hybrid supramolecular hydrogel added is 10-50g per square meter of saline-alkali soil, based on dry weight.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a cyclodextrin hybrid supramolecular hydrogel, wherein the building units of the cyclodextrin hybrid supramolecular hydrogel include quaternary ammonium salt modified β-cyclodextrin and lithium saponite that interacts electrostatically with the quaternary ammonium salt modified β-cyclodextrin; plant hormones are encapsulated within the cavity of the quaternary ammonium salt modified β-cyclodextrin.

[0016] The cyclodextrin hybrid supramolecular hydrogel (HEC&QAS-CD) of the present invention The cyclodextrin hybrid supramolecular hydrogel of this invention is composed of lithium saponite (HEC) and quaternary ammonium salt-modified β-cyclodextrin (QAS-CD). Electrostatic interactions exist between HEC and QAS-CD, forming a polymer network. The cavities of the QAS-CD effectively encapsulate plant hormones (SA), and the two are highly compatible. Based on electrostatic interactions, the cyclodextrin hybrid supramolecular hydrogel of this invention utilizes HEC for good water dispersibility and controllability, exhibiting high-viscosity colloid formation at low solid content. With QAS-CD as the host and plant hormones as the guest, it possesses the advantage of controlled release of plant hormones, potentially making it a highly efficient platform for promoting plant growth in saline-alkali soils. The cyclodextrin hybrid supramolecular hydrogel of this invention carries charges and cavities, enabling it to encapsulate plant hormones and synergistically promote plant growth in saline-alkali soils with phytoremediation, demonstrating high efficiency in saline-alkali soil remediation and effective plant growth promotion.

[0017] The cyclodextrin hybrid supramolecular hydrogel of this invention can integrate the properties of different plant hormones, adapt to various complex scenarios, and achieve diversified functions. The synergistic effect of the hybrid component lithium saponite and the polymer matrix quaternary ammonium salt modified β-cyclodextrin can improve the loading and controlled release efficiency of plant hormones.

[0018] This invention also provides a method for preparing the cyclodextrin hybrid supramolecular hydrogel described in the above technical solution. The preparation method provided by this invention has simple steps, is easy to operate, has high feasibility, and is suitable for industrial production.

[0019] This invention also provides the application of the cyclodextrin hybrid supramolecular hydrogel described in the above-described technical solutions, or the cyclodextrin hybrid supramolecular hydrogel prepared by the above-described technical solutions, in saline-alkali soils. The cyclodextrin hybrid supramolecular hydrogel is charged and has a cavity structure, which, combined with phytoremediation, promotes plant growth in saline-alkali soils, resulting in high environmental remediation efficiency and strong practicality. The cyclodextrin hybrid supramolecular hydrogel provided by this invention, in synergy with phytoremediation, improves the remediation effect on saline-alkali soils. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a scanning electron microscope image of lithium saponite from Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the supramolecular hydrogel of Example 1 of the present invention; Figure 3 The image shows the FT-IR spectrum of the supramolecular hydrogel in Example 1 of this invention. Figure 4 The above are scan images of the rheological properties and strain amplitude of the supramolecular hydrogel in Example 1 of this invention. Figure 5 This shows the changes in rapeseed biomass under the addition of different materials in the hydroponic experiment of Example 1. Figure 6 The changes in biomass of *Vigna edulis* (lower-arrow pea) with different materials were observed in the hydroponic experiment of Example 1. Figure 7 This illustrates the changes in maize biomass under different material additions in the soil cultivation experiment of Example 2. Figure 8 This shows the changes in biomass of *Vaccaria segetalis* when different materials were added in the soil cultivation experiment of Example 2. Detailed Implementation

[0022] The present invention provides a cyclodextrin hybrid supramolecular hydrogel, wherein the building units of the cyclodextrin hybrid supramolecular hydrogel include quaternary ammonium salt modified β-cyclodextrin and lithium saponite that interacts electrostatically with the quaternary ammonium salt modified β-cyclodextrin; The quaternary ammonium salt modified β-cyclodextrin contains plant hormones within its cavity.

[0023] In this invention, the quaternary ammonium salt modified β-cyclodextrin has the structural formula shown in Formula I: Formula I, In Formula I, n is the average degree of substitution of the quaternary ammonium salt, ranging from 2 to 7; in the embodiments of the present invention, the degree of substitution of the quaternary ammonium salt-modified β-cyclodextrin is 4.3.

[0024] In this invention, the preferred mass ratio of the quaternary ammonium salt modified β-cyclodextrin to lithium saponite is (56~168):1, specifically 17.8645g:160mg (i.e. 112:1).

[0025] In this invention, the plant hormone preferably includes one or more of indoleacetic acid, jasmonic acid, gibberellin, and salicylic acid; the structural formula of the indoleacetic acid is shown in Formula II: Formula II.

[0026] In this invention, the preferred molar ratio of the quaternary ammonium salt-modified β-cyclodextrin to the plant hormone is (1~10):1, specifically 10:1, 8:1, 6:1, 4:1, 2:1, or 1:1. The molar ratio described in this invention provides a good loading rate for the plant hormone.

[0027] The cyclodextrin hybrid supramolecular hydrogel provided by this invention uses quaternary ammonium salt modified β-cyclodextrin, which is a macrocyclic host obtained by replacing the hydroxyl groups on β-cyclodextrin with quaternary ammonium salt. It can form an inclusion complex of quaternary ammonium salt modified β-cyclodextrin and plant hormones through electrostatic interactions. Then, lithium saponite with a negative surface charge and the positively charged quaternary ammonium salt modified β-cyclodextrin containing plant hormones are constructed through electrostatic interactions to form a supramolecular hydrogel containing plant hormones.

[0028] This invention also provides a method for preparing the cyclodextrin hybrid supramolecular hydrogel described above, comprising the following steps: The stock solution was prepared by encapsulating a mixture of quaternary ammonium salt-modified β-cyclodextrin, plant hormone, and first water. The stock solution, lithium saponite, and second water were mixed to form a gel, resulting in the cyclodextrin hybrid supramolecular hydrogel.

[0029] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0030] This invention involves encapsulating quaternary ammonium salt-modified β-cyclodextrin, plant hormones, and first water to obtain a stock solution.

[0031] In this invention, the first water is preferably deionized water.

[0032] In this invention, the preferred ratio of the molar number of the quaternary ammonium salt-modified β-cyclodextrin to the volume of the first water is 10 mmol:(9~12) mL, specifically 10 mmol:9 mL, 10 mmol:10 mL, or 10 mmol:12 mL. This ratio ensures the preservation of viscoelasticity, strength, and other mechanical properties.

[0033] In this invention, the mixing of the quaternary ammonium salt-modified β-cyclodextrin, plant hormone, and first water is preferably performed by sequential stirring and ultrasonic mixing; the stirring speed is preferably 900~1300 rpm, specifically 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, or 1300 rpm; the stirring time is preferably 1~2 hours, specifically 1.5 hours; the ultrasonic mixing time is preferably 0.5~1.5 hours, specifically 0.75 hours or 1 hour. The mixture forms a stock solution containing the inclusion complex.

[0034] After obtaining the stock solution, the present invention mixes the stock solution, lithium saponite, and second water to form a gel, thereby obtaining the supramolecular hydrogel.

[0035] In this invention, the second water is preferably deionized water.

[0036] In this invention, the preferred ratio of the mass of lithium saponite to the volume of the stock solution is (1~2)g:(2.5~10)mL, specifically 1g:2.5mL, 2g:2.5mL, 1.5g:5mL or 1.6g:5mL.

[0037] In this invention, the mixing of the stock solution, lithium saponite, and second water is preferably carried out by: mixing and stirring lithium saponite and water until the solution becomes clear to obtain a lithium saponite aqueous solution; and then mixing and stirring the stock solution and the lithium saponite aqueous solution. The stirring speed for mixing the lithium saponite and water is preferably 480-960 rpm, specifically 480 rpm, 600 rpm, 720 rpm, 840 rpm, or 960 rpm, and the stirring time is preferably 20-40 min, specifically 25 min, 30 min, or 3 min. The stirring speed for mixing the stock solution and the lithium saponite aqueous solution is preferably 480-960 rpm, specifically 480 rpm, 600 rpm, 720 rpm, 840 rpm, or 960 rpm, and the stirring time is preferably 10-15 min, specifically 11 min, 12 min, or 15 min.

[0038] In this invention, the gelation temperature is preferably 15~40℃, specifically 20℃ or 25℃.

[0039] In this invention, the process after gelation (obtaining an aqueous gel) preferably further includes: freeze-drying the resulting product after allowing it to stand. To ensure gel formation and mechanical properties such as viscoelasticity and strength, the standing time is preferably 4~32 hours, specifically 12 hours or 24 hours. The freeze-drying preferably includes a pre-cooling stage and a drying stage sequentially; the temperature of the pre-cooling stage is preferably not higher than -40°C, specifically -40°C, -45°C, -50°C, -55°C or -60°C, and the pre-cooling stage time is preferably 1~1.5 hours, specifically 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours or 1.5 hours. The temperature of the drying stage is preferably -70~-50°C, specifically -70°C, -65°C, -60°C, -55°C or -50°C, and the drying stage time is preferably 48~72 hours, specifically 48 hours, 54 hours, 60 hours, 66 hours or 72 hours; the freeze-drying equipment is preferably a freeze dryer.

[0040] This invention also provides the application of the cyclodextrin hybrid supramolecular hydrogel described in the above technical solution or the cyclodextrin hybrid supramolecular hydrogel obtained by the preparation method described in the above technical solution in saline-alkali soil.

[0041] In this invention, the application includes the following steps: The cyclodextrin-hybridized supramolecular hydrogel was added to saline-alkali soil, and then plants were transplanted into the resulting mixed soil for cultivation, thereby restoring the saline-alkali soil. On a dry weight basis, the amount of the cyclodextrin hybrid supramolecular hydrogel added is 10-50g per square meter of saline-alkali soil.

[0042] This invention integrates cyclodextrin-hybrid supramolecular hydrogels with plants to form a repair system, which can promote plant growth.

[0043] In this invention, the process of transplanting the plant preferably includes adding a nutrient solution to the soil; the nutrient solution is preferably Hoagland nutrient solution or a prepared Hoagland nutrient solution. The preferred nutrient composition of the Hoagland nutrient solution includes: potassium sulfate 607 mg / L, ammonium dihydrogen phosphate 115 mg / L, magnesium sulfate 493 mg / L, EDTA iron sodium salt 20 mg / L, ferrous sulfate 2.86 mg / L, borax 4.5 mg / L, manganese sulfate 2.13 mg / L, copper sulfate 0.05 mg / L, zinc sulfate 0.22 mg / L, and ammonium sulfate 0.02 mg / L. The preferred method for preparing the Hoagland nutrient solution is as follows: mixing Hoagland nutrient solution, calcium salt, and water; the calcium salt is preferably calcium nitrate tetrahydrate; the water is preferably distilled water; the preferred mass ratio of Hoagland nutrient solution to calcium salt is 1260:945; the preferred mass ratio of the total amount of Hoagland in the Hoagland nutrient solution to water is 1.26:1000~4000, specifically 1.26:1000, 1.26:2000, 1.26:3000, or 1.26:4000. The mixing of the Hoagland nutrient solution, calcium salt, and water is preferably done by heating; the preferred heating temperature is simply enough to dissolve the Hoagland nutrient solution and calcium salt in the water.

[0044] In this invention, the plant is preferably one or more of economic crops or landscape plants; the economic crop is preferably one or two of corn and arrowhead pea; the landscape plant preferably includes one or more of reed, bamboo reed and water lily.

[0045] In this invention, the plant transplantation is preferably performed by transplanting the plant into a mixed soil, thereby dispersing the cyclodextrin-hybrid supramolecular hydrogel in the rhizosphere. Through this operation, the present invention ensures that the cyclodextrin-hybrid supramolecular hydrogel aggregates near the plant rhizosphere, thus enhancing the effective growth-promoting effect of the plant hormones released by the cyclodextrin-hybrid supramolecular hydrogel on plants.

[0046] In this invention, the preferred density of plant transplantation is 45-55 plants / m².2 Specifically, it can be 50 plants / m². 2 .

[0047] In this invention, the process preferably includes daily watering of the mixed soil after plant transplantation. The mass ratio of water to cyclodextrin-hybrid supramolecular hydrogel can be 50-150:0.2770-0.7354, specifically 75:0.3, 75:0.4, 75:0.5, 75:0.6, 75:0.7, 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, 100:0.7354, 125:0.3, 125:0.4, 125:0.5, 125:0.6, or 125:0.7. This invention, through water replenishment, helps restore and maintain the structure of the cyclodextrin-hybrid supramolecular hydrogel, thus facilitating its function.

[0048] To further illustrate the present invention, the cyclodextrin hybrid supramolecular hydrogels, their preparation methods, and applications provided by the present invention are described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1 The cyclodextrin hybrid supramolecular hydrogel prepared in this embodiment uses quaternary ammonium salt modified β-cyclodextrin (QAS-CD) purchased from Shandong Binzhou Zhiyuan Biotechnology Co., Ltd. as the host and indoleacetic acid (IAA) as the guest.

[0050] The preparation method of cyclodextrin hybrid supramolecular hydrogel includes the following steps: (1) Preparation of QAS-CD IAA stock solution: Mix QAS-CD and IAA at a molar ratio of 1:1. Specific steps include: Weigh 17.8645 g (10 mmol) of QAS-CD and 1.7518 g (10 mmol) of IAA into 10 mL of deionized water, stir to dissolve, and sonicate for 45 min to ensure complete dissolution and inclusion, obtaining the inclusion complex (QAS-CD). IAA (In-Acid Alcohol) stock solution.

[0051] The inclusion compound stock solution was dried in a freeze dryer to obtain a powdered inclusion compound (denoted as QAS-CD). IAA).

[0052] (2) Preparation of HEC&QAS-CD IAA supramolecular hydrogel: HEC (lithium saponite, 160 mg), QAS-CD The gel was prepared by mixing IAA (0.5 mL inclusion complex stock solution) and deionized water (4 mL). The specific steps included: first, mixing HEC and deionized water, adding a stir bar and stirring for 20 min until the solution became clear; then, the prepared QAS-CD... Add the IAA stock solution and continue stirring for 15 min; finally, dry it in a freeze dryer to obtain a dry gel (denoted as HEC&QAS-CD). IAA).

[0053] The properties of the supramolecular hydrogel were detected using a rheometer and scanning electron microscope, and its structure was observed using infrared spectroscopy and XRD. The results are as follows: Figures 1-4 As shown.

[0054] Figure 1 and Figure 2 The images shown are scanning electron microscope (SEM) images of lithium saponite and supramolecular hydrogel in this embodiment. It can be seen that lithium saponite is uniformly distributed in the gel.

[0055] Figure 3 The FT-IR spectrum of the supramolecular hydrogel in this embodiment shows that the structure of lithium saponite remained essentially unchanged during the gel formation process.

[0056] Figure 4 The image shows the rheological properties and strain amplitude test scans of the supramolecular hydrogel in this embodiment. It can be seen that in the low strain region, the storage modulus G′ (black curve) is much larger than the loss modulus G′′ (red curve), and both values ​​are basically stable. This indicates that the gel is in a stable network state dominated by elasticity in this range, with a dense structure and strong resistance to slight deformation.

[0057] Comparative Example 1 The only difference from Example 1 is that IAA inclusion is not performed; the remaining steps are the same as in Example 1, and the resulting dry gel is denoted as HEC&QAS-CD.

[0058] Application Example 1: Hydroponic Experiment Seedlings were raised in a greenhouse environment with daytime and nighttime temperatures of 30 ℃ / 25 ℃ and daytime and nighttime relative humidity of 70% / 90%, with a photoperiod of 12 h. Rapeseed and arrowhead pea seeds were selected and sown in seedling trays containing nutrient soil and vermiculite (3:1 v / v) substrate, respectively. After germination, the seedlings were allowed to develop two pairs of leaves.

[0059] Select seedlings that are uniform in size and growing well, and remove the soil attached to the roots of each plant; rinse the roots three times with deionized water, culture the plants in deionized water for 1 day, change the water, and continue to culture in deionized water until the plants grow white aquatic roots.

[0060] Transfer the solution to a glass culture bottle containing 150 mL of 1 / 2 strength Hoagland nutrient solution. Cover the bottle with a black bag to simulate a dark soil environment. Plant the plants using planting cotton and a planting basket at the bottle opening. Refill the bottle with nutrient solution daily until it reaches the mark. When the plants grow to about 10 cm in height, select uniform plants, replace the nutrient solution, and continue the experiment.

[0061] A typical stress environment was simulated by mixing NaCl and Na₂SO₄ at a ratio of 9 mol:1 mol, and 150 mL of a 1 / 2 Hoagland nutrient solution with a salt concentration of 200 mmol / L was prepared. The nutrient solution was added to each hydroponic bottle, and the bottles were aerated and stirred once a day for 1 min each time, with deionized water added to maintain the solution volume.

[0062] Add the frozen dry gel to the dialysis bag and seal it in a hydroponic bottle. After 5 days of hydroponics, the plants were rinsed, blanched, and dried to constant weight according to ASTM E1620-2016 "Standard Guide for the Determination of Biomass in Biological Samples". The remaining biomass was then quantified by weighing. Table 1 shows the experimental design of supramolecular hydrogel-plant hydroponics.

[0063] Table 1. Experimental Design Scheme for Supramolecular Hydrogel-Plant Hydroponics

[0064] The changes in biomass of hydroponically grown rapeseed and arrowhead pea under the addition of different materials in the hydroponic experiment are as follows: Figure 5 , 6 As shown.

[0065] The hydroponic experiment revealed significant differences in biomass between rapeseed and arrowhead vetch. Compared to the control group (CK), the biomass of both rapeseed and arrowhead vetch in the salt-alkali stress group was significantly reduced, indicating that plant growth is inhibited under salt-alkali stress. The different degrees of inhibition between rapeseed and arrowhead vetch may be due to differences in salt tolerance among plant species. Compared to the salt-alkali stress group, the biomass of the aboveground parts, roots, and whole plants of rapeseed and arrowhead vetch in different material addition groups was significantly increased.

[0066] For rapeseed ( Figure 5 Compared to the SS group, the whole plant biomass of the AA, LH, CA and AFM groups increased by 12%, 8%, 50% and 66% respectively, the root biomass increased by 26%, 5%, 65% and 92% respectively, and the aboveground biomass increased by 11%, 8%, 48% and 63% respectively.

[0067] For arrowhead peas ( Figure 6Compared to the SS group, the whole plant biomass of the AA, LH, CA and AFM groups increased by 26%, 44%, 85% and 95% respectively, the root biomass increased by 35%, 36%, 88% and 96% respectively, and the aboveground biomass increased by 22%, 48%, 83% and 94% respectively, showing a similar trend to that of rapeseed biomass.

[0068] Application Example 2: Soil Cultivation Experiment Soil cultivation experiments were conducted in a greenhouse environment with day / night temperatures of 25 ℃ / 30 ℃ and day / night relative humidity of 70% / 90%, with a photoperiod of 12 h. Corn and arrowhead peas were selected for pot experiments, using polyethylene pots, each containing 0.6 kg (dry weight) of mixed soil. Three experimental groups were set up, with ordinary farmland soil (without added materials) serving as a control. The ordinary farmland soil was taken from uncontaminated topsoil at Nankai University's Jinan Campus (E117°21′47.27″, N38°59′26.99″); the saline-alkali soil was taken from Ningxia, with a salinity of 7.53‰ and a pH of 9.12. After natural air drying, stones, impurities, and plant and animal remains were removed, the soil was crushed with a small wooden mallet, and sieved through a 2 mm sieve for later use. The specific experimental design is as follows: Table 2 Experimental Design of Supramolecular Hydrogel-Phytoremediation

[0069] Three uniformly sized seedlings were selected from each experimental group from the seedling trays. The nutrient soil attached to the roots of each plant was removed, and the seedlings were transplanted into flower pots, with one plant per pot. Each treatment had three replicates, with six pots per treatment, for a total of 18 pots. The plants were harvested after 45 days of growth, and plant and soil samples were collected and analyzed.

[0070] The changes in biomass of corn and arrowhead pea under different material additions in the soil culture experiment are as follows: Figure 7 , 8 As shown.

[0071] For corn ( Figure 7 Compared to the CK group, the biomass of plants in the SS and AFM groups was significantly reduced, with the whole plant biomass being 0.21 times and 0.28 times that of the CK group, the root biomass being 0.76 times and 0.83 times that of the CK group, and the aboveground biomass being 0.13 times and 0.20 times that of the CK group, respectively. Compared to the SS group, the whole plant biomass, root biomass, and aboveground biomass of the AFM group increased by 31%, 8%, and 53%, respectively.

[0072] For arrowhead peas ( Figure 8Compared to the CK group, the biomass of plants in the SS and AFM groups was significantly reduced, with the whole plant biomass being 0.12 times and 0.17 times that of the CK group, the root biomass being 0.50 times and 0.71 times that of the CK group, and the aboveground biomass being 0.06 times and 0.09 times that of the CK group, respectively. Compared to the SS group, the whole plant biomass, root biomass, and aboveground biomass of the AFM group increased by 45%, 41%, and 49%, respectively, showing a similar trend to that of maize biomass.

[0073] The above effects may be attributed to: on the one hand, the gel HEC&QAS-CD The addition of IAA alleviated salt-alkali stress; on the other hand, the slow release of indoleacetic acid promoted plant growth. In the example, HEC&QAS-CD... The addition of IAA gel can alleviate stress damage to plants, promote plant growth, improve growth efficiency, and help plants resist saline-alkali environments by regulating physiological and biochemical reactions, thereby improving soil structure and soil quality in subsequent growth and return to the field.

[0074] As can be seen from the above embodiments, the supramolecular hydrogel provided by the present invention has the function of promoting plant growth in saline-alkali soil and has high environmental remediation efficiency.

[0075] This invention synthesizes a supramolecular hydrogel (HEC&QAS-CD). Under saline-alkali stress conditions, the IAA (Induced Alkali Hydrogel) system, with its guest molecule slow-release system, can promote plant growth, while the gel adsorption system can alleviate the salt stress pressure on plant roots, prolong the action time of guest molecules, and thus improve the efficiency of plant, especially green manure, in improving saline-alkali soil. Compared with the saline-alkali stress group, the supramolecular hydrogel group showed increased plant biomass. Furthermore, the addition of the gel changes the traditional method of foliar spraying of plant hormones, using root application in the soil instead. This method is simpler, improves root utilization, and has a greater promoting effect on soil microorganisms.

[0076] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A cyclodextrin-hybrid supramolecular hydrogel, characterized in that, The building blocks of the cyclodextrin hybrid supramolecular hydrogel include quaternary ammonium salt modified β-cyclodextrin and lithium saponite that interacts electrostatically with the quaternary ammonium salt modified β-cyclodextrin. The quaternary ammonium salt modified β-cyclodextrin contains plant hormones within its cavity.

2. The cyclodextrin hybrid supramolecular hydrogel according to claim 1, characterized in that, The mass ratio of the quaternary ammonium salt modified β-cyclodextrin to lithium saponite is (56~168):

1.

3. The cyclodextrin hybrid supramolecular hydrogel according to claim 1, characterized in that, The plant hormones include one or more of indoleacetic acid, jasmonic acid, gibberellin, and salicylic acid.

4. The cyclodextrin hybrid supramolecular hydrogel according to claim 1 or 3, characterized in that, The molar ratio of the quaternary ammonium salt-modified β-cyclodextrin to the plant hormone is (1~10):

1.

5. The method for preparing the cyclodextrin hybrid supramolecular hydrogel according to any one of claims 1 to 4, characterized in that, Includes the following steps: The stock solution was prepared by encapsulating a mixture of quaternary ammonium salt-modified β-cyclodextrin, plant hormone, and first water. The stock solution, lithium saponite, and second water were mixed to form a gel, resulting in the cyclodextrin hybrid supramolecular hydrogel.

6. The preparation method according to claim 5, characterized in that, The molar ratio of the quaternary ammonium salt modified β-cyclodextrin to the volume of the first water is 10 mmol:(9~12) mL.

7. The preparation method according to claim 5, characterized in that, The mass ratio of the lithium saponite to the volume of the stock solution is (1~2)g:(2.5~10)mL.

8. The preparation method according to claim 5, characterized in that, The gel formation process further includes freeze drying, which includes a pre-cooling stage and a drying stage in sequence; the temperature of the pre-cooling stage is not higher than -40°C and the time is 1~1.5h; the temperature of the drying stage is -70~-50°C and the time is 48~72h.

9. The application of the cyclodextrin hybrid supramolecular hydrogel according to any one of claims 1 to 4 or the cyclodextrin hybrid supramolecular hydrogel obtained by the preparation method according to any one of claims 5 to 8 in saline-alkali soil.

10. The application according to claim 9, characterized in that, Includes the following steps: The cyclodextrin-hybridized supramolecular hydrogel was added to saline-alkali soil, and then plants were transplanted into the resulting mixed soil for cultivation, thereby restoring the saline-alkali soil. On a dry weight basis, the amount of the cyclodextrin hybrid supramolecular hydrogel added is 10-50g per square meter of saline-alkali soil.

Images