Preparation method and application of novel HDT hydrogel circularly used for cadmium adsorption and desorption
By developing a new HDT hydrogel, utilizing hyaluronic acid grafted with dopamine and tannin, the problem of cadmium pollution is solved, and the cadmium absorption and phytoremediation efficiency is effectively reduced in different polluted environments, providing an effective strategy for sustainable agriculture.
Patent Information
- Application Number
- CN202411848394.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-16
- Publication Date
- 2025-05-23
AI Technical Summary
The prior art is difficult to effectively solve the problem of cadmium pollution, especially in severely polluted areas, and there is a lack of dual network hydrogels that can support both plant growth and cadmium fixation.
A new HDT hydrogel was developed, which was prepared by grafting dopamine and tanninic acid hyaluronic acid through free radical condensation reaction, and has renewable, stable and efficient cadmium adsorption ability. The hydrogel reduces the absorption of cadmium by plants under mild contamination and improves phytorepair efficiency under severe contamination.
HDT hydrogel significantly reduces the absorption of cadmium by plants in different cadmium-contaminated environments, improves the efficiency of phytoremediation, and increases the total cadmium removal rate by 54% through its combination with sorghum, providing an effective solution for sustainable agriculture.
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Figure CN120022819A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of polymer materials and environmental restoration, and in particular to a preparation method and application of a novel HDT hydrogel cyclically used for cadmium adsorption and desorption. Background Art
[0002] Cadmium pollution is a critical environmental issue worldwide, mainly due to industrialization, increased mining activities, and widespread use of phosphate fertilizers. As a highly toxic heavy metal, cadmium poses a serious threat to ecosystem health and human well-being through its persistence in the environment and its tendency to bioaccumulate in the food chain. Various remediation technologies have been developed to address the cadmium pollution problem, including physical, chemical, and biological methods. Among these methods, the application of hydrogels has attracted widespread attention due to their high adsorption capacity, recyclability, and minimal risk of secondary pollution.
[0003] Hydrogels have unique properties such as high water absorption capacity, excellent mechanical strength, and the ability to be functionalized with various chemical groups, making them ideal candidates for heavy metal removal. Recent studies have shown that modified hydrogels can effectively immobilize cadmium ions in polluted environments while promoting plant growth. The combination of natural polymers and biocompatible materials in the synthesis of hydrogels has received special attention due to their environmental friendliness and renewability. Modified hydrogels with enhanced cadmium adsorption capacity and stability have shown promising results in water and soil remediation applications.
[0004] The combination of hydrogel technology and phytoremediation represents an innovative approach to improve remediation efficiency. This integrated strategy can potentially address the limitations of individual approaches, such as the long time required for phytoremediation alone and the need for sustainable, renewable materials for hydrogel-based approaches. Recent advances in hydrogel synthesis have focused on combining natural and renewable materials to improve sustainability. Tannic acid is a natural organic acid containing phenolic hydroxyl groups that is nontoxic and biodegradable and has been approved for use in food by the U.S. Food and Drug Administration. The combination of biopolymers such as hyaluronic acid with functional molecules such as dopamine and tannic acid provides promising opportunities for creating efficient and environmentally friendly remediation materials. However, research on the synergistic effects of hydrogels and sorghum in cadmium remediation remains limited, especially on the development of dual-network hydrogels that can simultaneously support plant growth and cadmium fixation. Therefore, the development of new hydrogel materials with enhanced properties such as pressure resistance, regeneration ability, and antibacterial properties is essential for practical applications.
[0005] The HDT hydrogel of the present invention has renewability, stability and high cadmium adsorption capacity. It reduces the absorption of cadmium by plants at light pollution levels and improves the efficiency of plant remediation in heavily polluted areas. This method provides a universal solution for sustainable agriculture, allowing safe production of crops in lightly contaminated soils, land reclamation in highly contaminated areas, and improving resource utilization in agricultural systems. The system is expected to protect crops from the accumulation of cadmium in lightly contaminated soils, improve the efficiency of plant remediation in heavily contaminated soils, and promote sustainable agricultural practices in affected areas. Overall, the combination of HDT hydrogel and sorghum planting shows great promise in addressing cadmium pollution in agriculture, providing a viable strategy for food production and soil remediation in affected areas. Summary of the invention
[0006] In view of the deficiencies in the prior art, the present invention provides a preparation method and application of a novel HDT hydrogel cyclically used for cadmium adsorption and desorption.
[0007] To achieve the above object, the present invention provides the following technical solutions: a preparation method and use of a novel HDT hydrogel cyclically used for cadmium adsorption and desorption, wherein the HDT hydrogel is obtained by a free radical condensation reaction of hyaluronic acid grafted with dopamine and tannic acid; The weight ratios of hyaluronic acid:dopamine:tannic acid are: 3:1:1, 2:2:1, 3:3:1, 3:2:1, 2:3:2, 1:1:3, 1:2:3, 1:2:1, 1:2:2, 2:1:3.
[0008] Preferably, dopamine is grafted onto hyaluronic acid through an amide condensation reaction, and tannic acid is grafted onto hyaluronic acid through an ester condensation reaction to obtain HA-DA-TA macromolecules, and then HDT hydrogel is prepared through the HA-DA-TA macromolecules.
[0009] Preferably, the preparation method of the polymer HA-DA-TA is as follows: dissolving hyaluronic acid in deionized water, adding EDCI / NHS to activate the carboxyl group, then adding dopamine, reacting at room temperature overnight, dialyzing in a dialysis bag with a molecular weight cutoff of 8000-14000Da for 1 day, then adding EDCI / NHS to activate the carboxyl group, adding tannic acid to the reaction solution, reacting at room temperature overnight, dialyzing for three days, and freeze-drying to obtain HA-DA-TA macromolecules.
[0010] Preferably, the preparation method of the HDT hydrogel is: preparing the hydrogel by dissolving HA-DA-TA, acrylamide and N,N-methylenebisacrylamide in 10 mL of pure water; adding ammonium persulfate and stirring for another 10 minutes, and then leaving the mixture to stand at room temperature for 8 hours to prepare the HDT hydrogel.
[0011] Preferably, after the HDT hydrogel absorbs water and swells, the HDT still has toughness and can efficiently adsorb cadmium ions. The cadmium ions can be quickly desorbed using 1M hydrochloric acid, and the cadmium ions can be adsorbed again after washing with deionized water. At the same time, the HDT hydrogel is stably present in aqueous solution for a long time and is stably present in 1M acid solution for many days.
[0012] Preferably, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy and mechanical compression stress are used for the characterization of HA-DA-TA and HDT hydrogels; The HDT hydrogels were placed in a culture dish, deionized water was added, and the hydrogels were weighed at different time intervals to analyze the swelling kinetics of the hydrogels and determine the time required for them to reach the maximum swelling capacity. The swelling capacity was calculated using the following formula: swelling capacity = W2-W1, where W1 represents the weight of the hydrogel before water absorption and W2 represents the weight of the swollen hydrogel. The swelling results were determined by the average of three separate experiments performed at room temperature.
[0013] Preferably, the HDT hydrogel is immersed in a high concentration of cadmium chloride (250 mM) solution, 10 μL of the solution sample is collected at different time points, and after dilution, the level of Cd2+ is measured using ICP-MS; HDT hydrogel can rapidly absorb cadmium ions within 4 hours, after which the absorption rate gradually decreases, ultimately reaching a balanced absorption capacity of 69% within 24 hours; Desorption was performed using 1 M hydrochloric acid solution, and the color of the hydrogel gradually became lighter within 20 min, indicating that H+ quickly replaced Cd. It was then washed three times with deionized water and completely recovered within 24 h.
[0014] Preferably, the HDT hydrogel has antibacterial activity. By measuring the size of the inhibition zone, the in vitro antibacterial activity of the HDT hydrogel against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was tested. The bacterial growth was significantly reduced, and the radius of the inhibition zone produced by all bacteria was above 2 mm.
[0015] The preparation method and use of a new HDT hydrogel for cyclic cadmium adsorption and desorption according to claim 1 is characterized in that: sorghum seedlings treated with HDT at low cadmium levels show normal growth and reduced cadmium absorption in the body, while sorghum seedlings treated with HDT at high cadmium levels show significant growth improvement relative to those not treated with HDT, and the combined use of HDT hydrogel and sorghum can increase the total cadmium removal rate by 54%.
[0016] Compared with the prior art, the present invention provides a preparation method and use of a novel HDT hydrogel for cyclic adsorption and desorption of cadmium, which has the following beneficial effects: 1. The preparation method and use of the new HDT hydrogel for cadmium adsorption and desorption in this cycle have renewability, stability and high cadmium adsorption capacity. Reduce plant absorption of cadmium at light pollution levels and improve phytoremediation efficiency in heavily polluted areas. This method provides a universal solution for sustainable agriculture, allowing safe production of crops in lightly contaminated soils, land reclamation in highly contaminated areas, and improving resource utilization in agricultural systems. The system is expected to protect crops from cadmium accumulation in lightly contaminated soils, improve phytoremediation efficiency in heavily contaminated soils, and promote sustainable agricultural practices in affected areas. Overall, the combination of HDT hydrogel and sorghum planting shows great promise in addressing cadmium pollution in agriculture, providing a viable strategy for food production and soil remediation in affected areas.
[0017] 2. Preparation method and use of the new HDT hydrogel for cadmium adsorption and desorption. The hydrogel has excellent pressure resistance, sustainable regeneration, 1M hydrochloric acid stability and antibacterial properties, and has an effective cadmium absorption capacity of 69%. In addition, sorghum seedlings treated with HDT at low cadmium levels showed normal growth and reduced cadmium absorption in the body. At the same time, sorghum seedlings treated with HDT at high cadmium levels showed significant growth improvement relative to seedlings without HDT treatment. The combined application of HDT hydrogel and sorghum can increase the total cadmium removal rate by 54%, proposing a promising strategy to reduce plant cadmium absorption and effectively utilize cadmium-contaminated land in different cadmium-contaminated environments. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 For the synthesis of HA-DA-TA macromolecules and HDT hydrogel.
[0019] Figure 2 Characterization of HDT hydrogels, including NMR, FT-IR and SEM images.
[0020] Figure 3 The characteristics of HDT hydrogel include the state change of HDT hydrogel before and after water swelling, the weight change curve of HDT hydrogel over time, the mechanical properties of HDT hydrogel after swelling and the compressive stress test of HDT hydrogel before swelling.
[0021] Figure 4 It is the adsorption, desorption and regeneration characteristics of HDT hydrogel.
[0022] Figure 5 Environmental stability test of HDT hydrogel, including water swelling of hydrogel fragments, cadmium adsorption, HCl desorption and stability.
[0023] Figure 6 The antibacterial activity of HDT hydrogel against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa.
[0024] Figure 7 The effect of HDT hydrogel on sorghum growth.
[0025] Figure 8 Application scenarios of HDT hydrogel. DETAILED DESCRIPTION
[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0027] See also Figure 1-Figure 8 , a preparation method and use of a novel HDT hydrogel for cyclic adsorption and desorption of cadmium, wherein the HDT hydrogel is obtained by a free radical condensation reaction of hyaluronic acid grafted with dopamine and tannic acid; The weight ratios of hyaluronic acid:dopamine:tannic acid are: 3:1:1, 2:2:1, 3:3:1, 3:2:1, 2:3:2, 1:1:3, 1:2:3, 1:2:1, 1:2:2, 2:1:3.
[0028] Dopamine is grafted onto hyaluronic acid through an amide condensation reaction, and tannic acid is grafted onto hyaluronic acid through an ester condensation reaction to obtain HA-DA-TA macromolecules, which are then used to make HDT hydrogels.
[0029] Example 1: Preparation of HDT hydrogel 1. Preparation of polymer HA-DA-TA 3.0 g of hyaluronic acid (HA) was dissolved in 100 mL of deionized water overnight. Then, 582.2 mg of N-hydroxysuccinimide (NHS) and 970.6 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) were added to the HA solution. Then, 2.0 g of solid dopamine hydrochloride (DA) was added. After stirring at room temperature for 12 hours, 582.2 mg of NHS, 970.6 mg of EDCI and 1 g of tannic acid (TA) were added to the solution again. After reacting at room temperature for 12 hours, the solution was dialyzed using a dialysis bag with a molecular weight cutoff of 8000-14000 Da. After 3 days, the solution was freeze-dried under reduced pressure to obtain high molecular weight HA-DA-TA.
[0030] 2. Preparation of HDT hydrogel The hydrogel was prepared by dissolving 600 mg HA-DA-TA, 300 mg acrylamide (AM), and 100 mg N,N-methylenebisacrylamide (MBA) in 10 mL pure water. 40 mg ammonium persulfate (APS) was added and stirred for another 10 minutes. The mixture was then left to stand at room temperature for 8 hours to prepare the HDT hydrogel.
[0031] like Figure 1 As shown in A, dopamine (DA) and hyaluronic acid (HA) undergo a condensation reaction, the carboxyl group combines with the amino group, and then the carboxyl group and the hydroxyl group also condense to form a high molecular weight HA-DA-TA. Figure 1 In B, the dried HA-DA-TA was mixed with acrylamide (AM), N,N'-methylenebisacrylamide (MBA) and deionized water and stirred thoroughly. Then, the initiator ammonium persulfate (APS) was added and the HDT hydrogel was formed after standing overnight.
[0032] Example 2: Structural characterization of HDT hydrogel Nuclear magnetic resonance (NMR) 1 H-NMR spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and mechanical compressive stress were used to characterize the HA-DA-TA and HDT hydrogels.
[0033] (1) Swelling behavior of HDT hydrogel The HDT hydrogels were placed in a culture dish, deionized water was added, and the weights were measured at different time intervals to analyze the swelling kinetics of the hydrogels and determine the time required for them to reach the maximum swelling capacity. The swelling capacity was calculated using the following formula: Swelling capacity = W 2 -W 1 , where W 1 represents the weight of the hydrogel before water absorption, W 2 The weight of the swollen hydrogel is represented by the swelling results determined by the average of three separate experiments performed at room temperature.
[0034] (2) Mechanical properties of HDT hydrogel like Figure 2 New peaks showing the presence of benzene rings in dopamine and tannic acid as well as 1 HNMR confirmed the synthesis of HA-DA-TA. FTIR showed the stretching vibration of C=O bonds in acid and amide. 2+ After exposure, spectral analysis showed a significant decrease in band intensity and contraction of the micrometer-scale pores to a wrinkled morphology. Figure 3 The results showed that the HDT hydrogel swelled in deionized water and maintained its structural integrity. Pressure tests showed that the HDT hydrogel had significant strain capacity and a maximum compressive strength of 60 kPa. These findings highlight the potential application of HDT hydrogel in water purification and remediation.
[0035] Example 3. Adsorption performance, regeneration and reusability of HDT hydrogel HDT hydrogels were immersed in a high concentration of cadmium chloride (250 mM) solution. 10 μL of the solution was sampled at different time points and diluted to measure Cd using ICP-MS. 2+ The results showed that HDT hydrogel could quickly absorb cadmium ions within 4 hours, and then the absorption rate gradually decreased, and finally reached a balanced absorption capacity of 69% within 24 hours ( Figure 4 ). Scanning electron microscopy images show that when cadmium is absorbed and reaches equilibrium, the hydrogel changes from the initial microporous network structure to a non-porous structure, indicating that cadmium ions penetrate into the micropores and cause the hydrogel to shrink to saturation. Desorption using 1M hydrochloric acid solution gradually lightens the color of the hydrogel within 20 minutes, indicating that H + Rapidly replace Cd. It was then washed three times with deionized water and fully recovered within 24 hours. Multiple adsorption-desorption-regeneration experiments proved that the hydrogel remained basically intact, with no weight loss, and showed long-lasting stability in deionized water. In addition, the hydrogel was crushed and placed in deionized water, gradually expanding to increase the contact area. After the adsorption-desorption-regeneration process, the colloid's absorption efficiency, desorption efficiency and regeneration efficiency of cadmium were significantly improved. The crushed hydrogel retained the characteristics of the intact hydrogel and remained stable in deionized water ( Figure 5 ).
[0036] Example 4: Determination of antibacterial activity of HDT hydrogel By measuring the size of the inhibition zone, the in vitro antibacterial activity of HDT hydrogel against Escherichia coli (E.coli, ATCC25922), Staphylococcus aureus (S.aureus, ATCC43300) and Pseudomonas aeruginosa (P.aeruginosa, ATCC10145) was tested. The results showed that bacterial growth was significantly reduced, and the radius of the inhibition zone produced by all bacteria was above 2mm, indicating that HDT hydrogel has strong antibacterial properties ( Figure 6 ).
[0037] Example 5: Effect of HDT hydrogel on sorghum growth under different cadmium pollution conditions This experiment explored the effect of HDT hydrogel on sorghum growth under different cadmium pollution levels. Under mild cadmium pollution (1 μM), there was no significant difference in growth parameters between plants treated with HDT hydrogel and the control group, indicating that the hydrogel did not interfere with the normal growth of plants. However, under low cadmium conditions, HDT hydrogel treatment reduced the absorption of cadmium by plants by 82%, making its cadmium content lower than the national feed safety standard, making it suitable as feed. In the presence of high concentrations of cadmium (500 μM), plants treated with HDT hydrogel showed significant stress resistance, with plant height, fresh weight and dry weight significantly higher than those of the untreated group, and no significant difference from the control group, indicating that the hydrogel effectively protected against severe cadmium stress. HDT hydrogel can also improve the water retention of plants, increasing the water content by 30%, and enhancing the stress resistance of plants. In addition, HDT hydrogel treatment reduced the accumulation of cadmium in plants by 50%, and combined with the hydrogel's own absorption of 69% of cadmium, it is expected that the total cadmium removal rate can be increased by 54%. These results indicate that HDT hydrogel can effectively reduce the negative impact of cadmium on sorghum and improve the plant's stress resistance, providing a basis for using hydrogel to repair heavy metal pollution.
[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium, characterized in that: The HDT hydrogel is obtained by free radical condensation reaction of hyaluronic acid grafted with dopamine and tannic acid; The weight ratios of hyaluronic acid:dopamine:tannic acid are: 3:1:1, 2:2:1, 3:3:1, 3:2:1, 2:3:2, 1:1:3, 1:2:3, 1:2:1, 1:2:2, 2:1:
3.
2. The method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium according to claim 1, characterized in that: Dopamine is grafted onto hyaluronic acid through an amide condensation reaction, and tannic acid is grafted onto hyaluronic acid through an ester condensation reaction to obtain HA-DA-TA macromolecules, which are then used to make HDT hydrogels.
3. The method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium according to claim 1, characterized in that: The preparation method of the polymer HA-DA-TA is as follows: dissolving hyaluronic acid in deionized water, adding EDCI / NHS to activate the carboxyl group, then adding dopamine, reacting at room temperature overnight, dialyzing in a dialysis bag with a molecular weight cutoff of 8000-14000Da for 1 day, then adding EDCI / NHS to activate the carboxyl group, adding tannic acid to the reaction solution, reacting at room temperature overnight, dialyzing for three days, and freeze-drying to obtain the HA-DA-TA macromolecule.
4. The method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium according to claim 1, characterized in that: The preparation method of the HDT hydrogel is as follows: the hydrogel is prepared by dissolving HA-DA-TA, acrylamide and N,N-methylenebisacrylamide in 10 mL of pure water; ammonium persulfate is added and stirred for another 10 minutes, and then the mixture is allowed to stand at room temperature for 8 hours to prepare the HDT hydrogel.
5. The method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium according to claim 1, characterized in that: After the HDT hydrogel absorbs water and swells, the HDT still has toughness and can efficiently adsorb cadmium ions. The cadmium ions can be quickly desorbed using 1M hydrochloric acid, and the cadmium ions can be adsorbed again after washing with deionized water. At the same time, the HDT hydrogel can exist stably in aqueous solution for a long time and can exist stably for many days in 1M concentration acid solution.
6. The method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium according to claim 1, characterized in that: Nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical compressive stress were used for the characterization of HA-DA-TA and HDT hydrogels; The HDT hydrogels were placed in a culture dish, deionized water was added, and the hydrogels were weighed at different time intervals to analyze the swelling kinetics of the hydrogels and determine the time required for them to reach the maximum swelling capacity. The swelling capacity was calculated using the following formula: swelling capacity = W2-W1, where W1 represents the weight of the hydrogel before water absorption and W2 represents the weight of the swollen hydrogel. The swelling results were determined by the average of three separate experiments performed at room temperature.
7. The method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium according to claim 1, characterized in that: The HDT hydrogel was immersed in a high concentration of cadmium chloride (250 mM) solution, and 10 μL of solution samples were collected at different time points. After dilution, the level of Cd2+ was measured using ICP-MS; HDT hydrogel can rapidly absorb cadmium ions within 4 hours, after which the absorption rate gradually decreases, ultimately reaching a balanced absorption capacity of 69% within 24 hours; Desorption was performed using 1 M hydrochloric acid solution, and the color of the hydrogel gradually became lighter within 20 min, indicating that H+ quickly replaced Cd. It was then washed three times with deionized water and completely recovered within 24 h.
8. The method for preparing a novel HDT hydrogel for cyclic adsorption and desorption of cadmium according to claim 1, characterized in that: HDT hydrogel has antibacterial activity. By measuring the size of the inhibition zone, the in vitro antibacterial activity of HDT hydrogel against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was tested. The bacterial growth was significantly reduced, and the radius of the inhibition zone produced by all bacteria was above 2 mm.
9. A use of a novel HDT hydrogel for cyclic adsorption and desorption of cadmium, characterized in that: Sorghum seedlings treated with HDT hydrogel at low cadmium levels showed normal growth and reduced cadmium uptake in vivo, while sorghum seedlings treated with HDT hydrogel at high cadmium levels showed significant growth improvement relative to no HDT treatment. The combined application of HDT hydrogel and sorghum increased the total cadmium removal rate by 54%.