Hydrogel-based curing agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of environmental remediation materials, in particular to a hydrogel-based curing agent as well as a preparation method and application thereof. The hydrogel-based curing agent provided by the invention can repair engineering construction repair scenes prone to water and soil loss for a long time at a time, and is short in repair period, low in cost and good in repair effect. Specifically, the invention discloses a bio-based ionic cross-linked hydrogel curing agent, sodium alginate and chitosan are taken as base materials, the structural stability is enhanced through double-particle-size nano bentonite, and a water erosion resistant curing shell layer can be quickly formed by combining the fertilizer retention function of polyglutamic acid, so that long-acting repair of a red clay slope is realized, the repair period is short, the cost is low, and the curing agent has a wide application prospect. The method is suitable for water and soil loss prevention and control projects.

Description

Technical Field

[0001] This invention relates to the field of soil solidification and ecological restoration materials technology, and in particular to a hydrogel-based solidifying agent, its preparation method and application. Background Technology

[0002] Environmental remediation, as one of the main methods of ecological protection, primarily includes physical remediation, chemical remediation, bioremediation, and engineering remediation. Furthermore, technicians will comprehensively apply these approaches based on the type of pollution, remediation objectives, and environmental conditions to better achieve environmental remediation goals. Among these, bioremediation mainly utilizes the metabolic activities of organisms to complete environmental remediation, offering advantages such as low cost and environmental friendliness, and is currently an important direction for the development of environmental remediation.

[0003] With increasing awareness of ecological security, post-construction environmental remediation has become a crucial aspect of the engineering construction field. How to effectively and quickly complete environmental remediation has become a key focus for environmental remediation researchers. Post-construction environmental remediation mainly includes scenarios such as highway slope greening, surface restoration after mining, and greening restoration of masonry works.

[0004] For the aforementioned restoration scenarios, technicians currently primarily utilize bioremediation to achieve environmental restoration. Technicians disperse soil on the slope surface and then plant various vegetation, a simple and convenient method. However, this method also has significant drawbacks. For example, the soil on the slope surface has poor adhesion and is easily washed away by rainwater, especially during the rainy season. This results in insufficient soil fertility on the restored surface, limiting plant growth and significantly reducing the overall restoration effect. Furthermore, the labor, material, and time costs associated with secondary restoration are very high. In addition, traditional chemical hardeners (such as cement and lime) can cause secondary pollution to the restored surface. Traditional bio-based hardeners, due to their weak erosion resistance and short fertilization retention period (3-6 months), perform poorly in terms of long-term effectiveness and fertilization retention, failing to meet the long-term vegetation restoration needs of 1-2 years after engineering restoration.

[0005] In conclusion, how to carry out one-time long-term restoration of slopes and other areas prone to soil erosion is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a hydrogel-based curing agent, its preparation method and application. The hydrogel-based curing agent provided by the present invention can provide one-time long-term repair of engineering construction repair scenarios prone to soil erosion, with short repair cycle, low cost and good repair effect.

[0007] This invention provides a hydrogel-based curing agent, comprising the following raw materials in parts by weight: 8-15 parts sodium alginate, 3-8 parts chitosan, 1-3 parts acetic acid, 2-6 parts calcium chloride, 4-10 parts nano-bentonite, 0.5-2 parts polyglutamic acid, and 50-80 parts water.

[0008] Preferably, the sodium alginate contains 72-83% mannuronic acid (M unit).

[0009] Preferably, the nano-bentonite includes a first nano-bentonite and a second nano-bentonite; the particle size of the first nano-bentonite is 20-60 nanometers; and the particle size of the second nano-bentonite is 70-80 nanometers.

[0010] Preferably, the mass ratio of the first nano-bentonite to the second nano-bentonite is 100:20~35.

[0011] Preferably, the number-average molecular weight of the polyglutamic acid is 70,000 to 120,000 Da.

[0012] The present invention also provides a method for preparing the hydrogel-based curing agent described above, comprising the following steps: (1) Sodium alginate, water, nano-bentonite, chitosan, acetic acid and calcium chloride were mixed and subjected to ionic cross-linking reaction to obtain hydrogel complex; (2) The hydrogel complex and polyglutamic acid are mixed to obtain the hydrogel-based curing agent.

[0013] The present invention also provides the application of the hydrogel-based curing agent described in the above-described scheme or the hydrogel-based curing agent obtained by the preparation method described in the above-described scheme in the field of environmental remediation.

[0014] The present invention also provides environmental remediation soil particles, comprising the following components in parts by weight: 100 parts red clay, 5-10 parts bamboo shavings, 3-6 parts tea seed husks, 5-7 parts animal manure, 15-25 parts hydrogel-based curing agent, and 20-30 parts water; wherein the hydrogel-based curing agent is the hydrogel-based curing agent described in the above scheme or the hydrogel-based curing agent obtained by the preparation method described in the above scheme.

[0015] Preferably, the particle size of the environmental remediation soil particles is 2-5 mm.

[0016] This invention also provides a method for preparing the environmental remediation soil particles described above, comprising the following steps: Red clay, bamboo shavings, tea seed shells, animal manure, hydrogel-based curing agent, and water are mixed and granulated in a drum to obtain the environmental remediation soil particles.

[0017] This invention provides a hydrogel-based curing agent. The hydrogel-based curing agent provided by this invention can provide one-time, long-lasting repair for engineering construction sites prone to soil erosion, with a short repair cycle, low cost, and good repair effect. Specifically, the hydrogel-based curing agent provided by this invention is a bio-based ion-crosslinked hydrogel curing agent. It uses a natural biopolymer (sodium alginate) as the core substrate, constructing a three-dimensional network structure through ion crosslinking (sodium alginate undergoes ion crosslinking with chitosan and calcium chloride; the carboxyl groups on the sodium alginate molecular chain and the amino groups on the chitosan molecular chain form a preliminary crosslinking network through ionic bonds; calcium ions in calcium chloride form ionic bonds with the carboxyl groups on the sodium alginate molecular chain, constructing a three-dimensional network structure; nano-bentonite is distributed within the three-dimensional network structure, entangled and adsorbed with the three-dimensional network structure, strengthening the three-dimensional network structure and improving its mechanical properties). Utilizing the high water absorption and retention properties of sodium alginate and the structural stability of the ion-crosslinked network, it can quickly penetrate the soil and aggregate soil particles, forming a solidified shell layer with anti-water erosion and anti-disintegration properties, significantly improving the mechanical strength and stability of the slope surface, and effectively maintaining the soil, its fertility, and moisture. Furthermore, polyglutamic acid works synergistically with the aforementioned three-dimensional network structure. Through the carboxyl groups on its molecular chain, polyglutamic acid chelates nutrients such as nitrogen, phosphorus, and potassium in the soil, forming a "water-fertilizer dual-locking" mechanism with the water-retention function of the three-dimensional network structure. This slows down nutrient loss and provides a long-term, stable supply of nutrients for plant growth. The hydrogel-based curing agent provided by this invention is suitable for engineering scenarios such as slope treatment and soil erosion control in red clay areas, and has good application prospects and ecological benefits.

[0018] Furthermore, the first and second nano-bentonite together produce a triple effect of "pore filling, mechanical enhancement, and moisture regulation". The first nano-bentonite fills the pores of the three-dimensional network structure and improves the density of the structure; the second nano-bentonite enhances the mechanical interlocking of the three-dimensional network structure with the environmental remediation soil particles, while regulating the water infiltration rate, achieving the dual effects of mechanical stability and slow water release.

[0019] This invention also provides a method for preparing the hydrogel-based curing agent described in the above-mentioned scheme. The preparation method provided by this invention is convenient to operate, uses environmentally friendly raw materials, has low investment costs, good safety, and stable processes, and possesses the basic conditions for industrial production.

[0020] This invention also provides the application of the hydrogel-based curing agent described in the above-described scheme or the hydrogel-based curing agent prepared by the above-described scheme in the field of environmental remediation. The hydrogel-based curing agent provided by this invention is suitable for use in the field of environmental remediation, such as in red clay slope treatment, soil erosion control, or soil remediation after engineering construction. When performing slope protection or soil solidification, it can effectively improve the surface stability of red clay slopes, achieve ideal remediation results, and is convenient to construct.

[0021] This invention also provides environmental remediation soil particles. The environmental remediation soil particles provided by this invention, through the combination of the hydrogel-based curing agent and components in the above-mentioned scheme, have the function of absorbing water during rainfall and releasing water during drought, possessing long-lasting fertility and adhesion. They not only prevent soil erosion during the rainy season but also have water and fertilizer retention effects. They are suitable for engineering construction and remediation scenarios prone to soil erosion, such as greening of highway slopes, exposed rock masses after mining, or road engineering projects. They offer low remediation costs, good remediation effects, and broad application prospects.

[0022] This invention also provides a method for preparing the environmental remediation soil particles described above. The preparation method provided by this invention is low-cost, simple in procedure, and has significant economic benefits. The environmental remediation soil particles provided by this invention have long-lasting remediation effects, significantly reduce the cost of environmental remediation, and have significant social benefits. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of this invention, the accompanying drawings used in the embodiments of this invention or in the prior art are briefly described below. For those skilled in the art, other drawings can be derived from the following drawings without creative effort, and all such drawings are within the protection scope of this invention.

[0024] Figure 1 The results are for Test Example 1; where a is the soil coverage rate at 180 days, b is the soil coverage rate at 360 days, c is the vegetation coverage rate at 180 days, and d is the vegetation coverage rate at 360 days. Detailed Implementation

[0025] This invention provides a hydrogel-based curing agent, comprising the following raw materials in parts by weight: 8-15 parts sodium alginate, 3-8 parts chitosan, 1-3 parts acetic acid, 2-6 parts calcium chloride, 4-10 parts nano-bentonite, 0.5-2 parts polyglutamic acid, and 50-80 parts water.

[0026] The hydrogel-based curing agent provided by the present invention comprises 8 to 15 parts of sodium alginate, preferably 9 to 14 parts, more preferably 10 to 12 parts, and even more preferably 11 parts, by weight.

[0027] In this invention, the proportion of mannouronic acid (M unit) in the sodium alginate is preferably 72-83%, more preferably 74-78%.

[0028] Based on the mass fraction of sodium alginate, the hydrogel-based curing agent provided by the present invention comprises 3 to 8 parts of chitosan, preferably 4.5 to 7 parts, more preferably 5 to 6.5 parts, and even more preferably 6 parts.

[0029] In this invention, the number average molecular weight of the chitosan is preferably 200,000 to 300,000 Da, and more preferably 230,000 to 270,000 Da.

[0030] Based on the mass fraction of sodium alginate, the hydrogel-based curing agent provided by the present invention includes 1 to 3 parts of acetic acid, preferably 1.5 to 2.5 parts, and more preferably 2 parts.

[0031] Based on the mass fraction of sodium alginate, the hydrogel-based curing agent provided by the present invention comprises 2 to 6 parts of calcium chloride, preferably 3 to 5 parts, and more preferably 4.5 parts.

[0032] Based on the mass fraction of sodium alginate, the hydrogel-based curing agent provided by the present invention comprises 4 to 10 parts of nano-bentonite, preferably 5 to 8 parts, and more preferably 6 parts.

[0033] In this invention, the nano-bentonite preferably includes a first nano-bentonite and a second nano-bentonite; the particle size of the first nano-bentonite is preferably 20-60 nanometers, more preferably 30-50 nanometers, and even more preferably 35-50 nanometers; the particle size of the second nano-bentonite is preferably 70-80 nanometers; the mass ratio of the first nano-bentonite to the second nano-bentonite is preferably 100:20-35, more preferably 100:25-30. This invention employs nano-bentonite with the aforementioned particle size distribution and controls the ratio of the two components. On one hand, this significantly improves the dispersion effect of the nano-bentonite in the three-dimensional network structure, resulting in a marked improvement in the performance uniformity of the three-dimensional network structure. On the other hand, the first nano-bentonite, with its small particle size advantage, more easily adsorbs calcium ions in the three-dimensional network structure, while the second nano-bentonite, with its large particle size advantage, can simultaneously form a significant binding effect with the first nano-bentonite and chitosan. This further enriches the three-dimensional network structure, improves the adhesion and mechanical properties of the hydrogel-based curing agent, and enhances its morphology retention during subsequent use. This largely avoids the failure of the three-dimensional network structure due to external forces and other factors, while ensuring its adhesion and curing performance. The overall performance is excellent and balanced.

[0034] Based on the mass fraction of sodium alginate, the hydrogel-based curing agent provided by the present invention includes 0.5 to 2 parts of polyglutamic acid, preferably 0.8 to 1.6 parts, and more preferably 1 to 1.3 parts.

[0035] In this invention, the number-average molecular weight of the polyglutamic acid is preferably 70,000 to 120,000 Da, and more preferably 80,000 to 100,000 Da.

[0036] Based on the mass fraction of sodium alginate, the hydrogel-based curing agent provided by the present invention comprises 50-80 parts of water, preferably 60-70 parts, and more preferably 65 parts.

[0037] In this invention, the water is preferably deionized water.

[0038] The present invention also provides a method for preparing the hydrogel-based curing agent described above, comprising the following steps: (1) Sodium alginate, water, nano-bentonite, chitosan, acetic acid and calcium chloride were mixed and subjected to ionic cross-linking reaction to obtain hydrogel complex; (2) The hydrogel complex and polyglutamic acid are mixed to obtain the hydrogel-based curing agent.

[0039] This invention involves mixing sodium alginate, water, nano-bentonite, chitosan, acetic acid, and calcium chloride (denoted as the first mixture) and performing an ionic crosslinking reaction to obtain a hydrogel composite. In this invention, the first mixture preferably includes the following steps: premixing sodium alginate and a first portion of water to obtain a premix; then mixing the premix with nano-bentonite (denoted as mixture A) to obtain a mixed solution; subsequently, mixing the mixed solution with chitosan, acetic acid, and a second portion of water (denoted as mixture B) to obtain a composite solution; and finally, mixing the composite solution with calcium chloride and the remaining water (denoted as mixture C).

[0040] In this invention, the first portion of water accounts for 45-65% of the total mass of water, more preferably 50-60%, and even more preferably 55%.

[0041] In this invention, the premixing is preferably stirring; the stirring speed is preferably 100~300 rpm, more preferably 200 rpm, and the stirring time is preferably 15~30 minutes, more preferably 20~25 minutes.

[0042] In this invention, the mixture A is preferably ultrasonically dispersed; the power of the ultrasonic dispersion is preferably 150~300W, more preferably 200~250W, and the ultrasonic dispersion time is preferably 30~50 minutes, more preferably 35~45 minutes, and even more preferably 40 minutes.

[0043] In this invention, the second portion of water accounts for 15-30% of the total water mass, more preferably 20-25%.

[0044] In this invention, the mixture B is preferably stirred; the stirring speed is preferably 100~300 rpm, more preferably 200 rpm, and the stirring time is preferably 10~30 minutes, more preferably 15~20 minutes.

[0045] In this invention, the mixture C preferably includes the following steps: mixing calcium chloride and the remaining water (denoted as mixture D) to obtain a calcium chloride solution, and then adding the calcium chloride solution dropwise into the composite liquid.

[0046] In this invention, the mixing D is preferably stirring; the stirring speed is preferably 80~120 rpm, and the stirring time is preferably 5~15 minutes, more preferably 10 minutes.

[0047] In this invention, the dripping rate is preferably 50-120 drops / minute, more preferably 60-90 drops / minute, and even more preferably 80 drops / minute.

[0048] In this invention, the temperature of the ion crosslinking reaction is preferably room temperature; the room temperature is preferably 20-35 degrees Celsius, more preferably 25-30 degrees Celsius; the time of the ion crosslinking reaction is preferably 1-2 hours, more preferably 1.2-1.6 hours, and even more preferably 1.5 hours.

[0049] After obtaining the hydrogel composite, the present invention mixes the hydrogel composite with polyglutamic acid (denoted as the second mixture) to obtain the hydrogel-based curing agent. In the present invention, the second mixture is preferably stirred; the stirring speed is preferably 200~350 rpm, more preferably 250~300 rpm, and the stirring time is preferably 25~50 minutes, more preferably 30~40 minutes.

[0050] The present invention also provides the application of the hydrogel-based curing agent described in the above-described scheme or the hydrogel-based curing agent obtained by the preparation method described in the above-described scheme in the field of environmental remediation.

[0051] The hydrogel-based curing agent provided by this invention is suitable for use in the field of environmental remediation for slope protection or soil solidification. It can improve the surface stability of red clay slopes, achieve ideal repair results, and is easy to construct.

[0052] The present invention also provides environmental remediation soil particles, comprising the following components in parts by weight: 100 parts red clay, 5-10 parts bamboo shavings, 3-6 parts tea seed husks, 5-7 parts animal manure, 15-25 parts hydrogel-based curing agent, and 20-30 parts water; wherein the hydrogel-based curing agent is the hydrogel-based curing agent described in the above scheme or the hydrogel-based curing agent obtained by the preparation method described in the above scheme.

[0053] The environmental remediation soil particles provided by this invention comprise 100 parts by weight of red clay.

[0054] In this invention, the red clay is preferably red clay from Jiangxi province. This invention modifies red clay prone to soil erosion to produce environmentally friendly soil remediation particles, fully demonstrating the excellent performance of the hydrogel-based curing agent provided by this invention. It is expected that this agent can be used on other soils that are relatively less prone to soil erosion, with even better results.

[0055] Based on the mass fraction of the red clay, the environmental remediation soil particles provided by the present invention include 5 to 10 parts of bamboo chips, preferably 7 to 8 parts.

[0056] Based on the mass fraction of the red clay, the environmental remediation soil particles provided by the present invention include 3 to 6 parts of tea seed husks, preferably 4 to 5 parts.

[0057] Based on the mass fraction of the red clay, the environmental remediation soil particles provided by the present invention include 5 to 7 parts of animal feces, preferably 6 parts.

[0058] In this invention, the animal excrement preferably includes cow dung.

[0059] Based on the mass fraction of the red clay, the environmental remediation soil particles provided by the present invention include 15-25 parts of hydrogel-based curing agent, preferably 18-23 parts, and more preferably 20-21 parts.

[0060] Based on the mass fraction of the red clay, the environmental remediation soil particles provided by the present invention include 20-30 parts of water, preferably 22-27 parts, and more preferably 25 parts.

[0061] In this invention, the particle size of the environmental remediation soil particles is preferably 2-5 mm, more preferably 3-4 mm.

[0062] This invention also provides a method for preparing the environmental remediation soil particles described above, comprising the following steps: Red clay, bamboo shavings, tea seed shells, animal manure, hydrogel-based curing agent, and water are mixed and granulated in a drum to obtain the environmental remediation soil particles.

[0063] In this invention, the rotation speed of the drum granulator is preferably 3~5 rpm, more preferably 4 rpm, and the feeding rate is preferably 5~10 kg / h, more preferably 8 kg / h.

[0064] In this invention, the process after roller granulation preferably includes curing the resulting product; the curing temperature is preferably 23~27℃, more preferably 25℃, the relative humidity is preferably 55~65%, more preferably 60%, and the curing time is preferably 7 days. Through the above curing process, this invention enhances the bonding strength between the hydrogel-based curing agent and other components in the environmentally remediated soil particles.

[0065] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0066] Example 1 This embodiment provides a hydrogel-based curing agent, the specific raw materials used are as follows: 15 kg of sodium alginate (M unit ratio of 74%), 8 kg of chitosan (number average molecular weight of 270,000 Da), 3 kg of acetic acid, 6 kg of calcium chloride, 10 kg of nano-bentonite (the first nano-bentonite has a particle size of 60 nm, the second nano-bentonite has a particle size of 80 nm, and the mass ratio of the first nano-bentonite to the second nano-bentonite is 100:20), 2 kg of polyglutamic acid (number average molecular weight of 100,000 Da), and 80 kg of water.

[0067] The preparation method of the hydrogel-based curing agent in this embodiment includes the following specific steps: Sodium alginate and a portion of water (55 wt% of total water) were stirred at 200 rpm for 25 minutes to obtain a premix. The premix was then ultrasonically dispersed with nano-bentonite at 250 W for 45 minutes to obtain a mixed solution. This mixed solution, along with chitosan, acetic acid, and a portion of water (20 wt% of total water), was stirred at 200 rpm for 20 minutes to obtain a composite solution. Calcium chloride and the remaining water were then stirred at 100 rpm for 10 minutes to obtain a calcium chloride solution. This calcium chloride solution was then added dropwise to the composite solution at a rate of 80 drops / minute, and the mixture was subjected to an ionic crosslinking reaction at room temperature for 1.5 hours to obtain a hydrogel composite. The prepared hydrogel composite was then stirred with polyglutamic acid at 300 rpm for 40 minutes to obtain a hydrogel-based curing agent.

[0068] This embodiment also prepares an environmental remediation soil particle, using a hydrogel-based curing agent prepared in this embodiment, with the following components: 100 kg red clay, 10 kg bamboo shavings, 6 kg tea seed husks, 7 kg cow dung, 25 kg hydrogel-based curing agent, and 30 kg water.

[0069] This invention also provides a method for preparing the environmental remediation soil particles described above, comprising the following steps: Red clay, bamboo shavings, tea seed shells, cow manure, hydrogel-based curing agent, and water were mixed and granulated in a drum. The rotation speed was controlled at 4 rpm and the feeding rate was 8 kg / h. The mixture was then cured for 7 days at 23-27℃ and 55-65% relative humidity to obtain environmental remediation soil particles with a particle size distribution of 2-5 mm.

[0070] Example 2 The preparation method in this embodiment is the same as that in Example 1, except that the specific raw materials used in the hydrogel-based curing agent are as follows: 8 kg of sodium alginate (M unit ratio of 74%), 3 kg of chitosan (number average molecular weight of 270,000 Da), 1 kg of acetic acid, 2 kg of calcium chloride, 4 kg of nano-bentonite (the first nano-bentonite has a particle size of 40 nm, the second nano-bentonite has a particle size of 70 nm, and the mass ratio of the first nano-bentonite to the second nano-bentonite is 100:35), 0.5 kg of polyglutamic acid (number average molecular weight of 100,000 Da), and 60 kg of water.

[0071] Example 3 The preparation method in this embodiment is the same as that in Example 1, except that the specific raw materials used in the hydrogel-based curing agent are as follows: 12 kg of sodium alginate (M unit ratio of 74%), 7 kg of chitosan (number average molecular weight of 270,000 Da), 2.5 kg of acetic acid, 5 kg of calcium chloride, 8 kg of nano-bentonite (the first nano-bentonite has a particle size of 20 nm, the second nano-bentonite has a particle size of 70 nm, and the mass ratio of the first nano-bentonite to the second nano-bentonite is 100:25), 1 kg of polyglutamic acid (number average molecular weight of 100,000 Da), and 70 kg of water.

[0072] Example 4 The preparation method in this embodiment is the same as that in Example 1, except that the specific raw materials used in the hydrogel-based curing agent are as follows: 10 kg sodium alginate (M unit ratio 74%), 4 kg chitosan (number average molecular weight 270,000 Da), 3 kg acetic acid, 6 kg calcium chloride, 5 kg nano-bentonite (the first nano-bentonite has a particle size of 20 nm, the second nano-bentonite has a particle size of 80 nm, and the mass ratio of the first nano-bentonite to the second nano-bentonite is 100:20), 1.5 kg polyglutamic acid (number average molecular weight 100,000 Da), and 65 kg water.

[0073] Example 5 The preparation method in this embodiment is the same as in Example 1, except that the composition of the environmental remediation soil particles is as follows: 100 kg red clay, 5 kg bamboo shavings, 3 kg tea seed husks, 5 kg cow dung, 15 kg hydrogel-based curing agent, and 23 kg water.

[0074] Example 6 The preparation method in this embodiment is the same as in Example 1, except that the composition of the environmental remediation soil particles is as follows: 100 kg red clay, 10 kg bamboo shavings, 4 kg tea seed husks, 6 kg cow dung, 20 kg hydrogel-based curing agent, and 25 kg water.

[0075] Example 7 The preparation method in this embodiment is the same as in Example 1, except that the composition of the environmental remediation soil particles is as follows: 100 kg red clay, 8 kg bamboo shavings, 5 kg tea seed husks, 6 kg cow dung, 20 kg hydrogel-based curing agent, and 28 kg water.

[0076] Example 8 The preparation method of this embodiment is the same as that of Example 1, except that the number average molecular weight of polyglutamic acid is 70,000 Da.

[0077] Example 9 The preparation method of this embodiment is the same as that of Example 1, except that the number average molecular weight of polyglutamic acid is 120,000 Da.

[0078] Example 10 The preparation method of this embodiment is the same as that of Example 1, except that the number average molecular weight of chitosan is 300,000 Da.

[0079] Comparative Example 1 The preparation method of this comparative example is the same as that of Example 1, except that calcium chloride was not added.

[0080] Comparative Example 2 The preparation method of this comparative example is the same as that of Example 1, except that the second nano-bentonite is replaced with an equal mass of the first nano-bentonite.

[0081] Comparative Example 3 The preparation method of this comparative example is the same as that of Example 1, except that the proportion of sodium alginate M unit is 50%.

[0082] Comparative Example 4 The preparation method of this comparative example is the same as that of Example 1, except that chitosan was not added.

[0083] Comparative Example 5 The preparation method of this comparative example is the same as that of Example 1, except that no hydrogel-based curing agent was added to the environmental remediation soil particles.

[0084] Test Example 1 Mechanical properties of the environmental remediation soil particles prepared in Examples 1-10 and Comparative Examples 1-5 were tested. The compressive strength was tested by unconfined compressive strength test (according to GB / T 50123-2019), and the anti-disintegration rate was determined by dry-wet cycle test (the environmental remediation soil particles were taken, their initial mass m0 was accurately weighed with a balance, placed in a dry-wet cycle chamber and dried at 60°C to constant weight and soaked in water at room temperature for 5 hours, cycled 10 times, the loose particles on the surface were gently rinsed with clean water, dried to constant weight and weighed, and the mass m1 was calculated). The results are shown in Table 1.

[0085] Table 1. Mechanical properties of environmental remediation soil particles from Examples 1-10 and Comparative Examples 1-5

[0086] As shown in Table 1, compared with Examples 1-10, Comparative Example 1 did not add calcium chloride, and Comparative Example 4 did not add chitosan, resulting in a simple network structure formed by sodium alginate ion crosslinking, and a significant decrease in adhesion and mechanical properties. Comparative Example 2 did not add second nano-bentonite, which caused the effect of the second nano-bentonite and calcium ions to disappear, and further binding effect to disappear, resulting in a significant decrease in adhesion and mechanical properties. The compressive strength of Comparative Example 3 was higher than that of Examples 1-10, but the disintegration rate was only 70.82%. This is because the M unit ratio of sodium alginate in Comparative Example 3 was only 50%, which led to a decrease in ion crosslinking density. The hardness of the hydrogel network increased, but the toughness decreased. It was easy to crack and disintegrate after contact with water, so the disintegration rate was significantly reduced. Comparative Example 5 did not add a hydrogel-based curing agent, which prevented other components from binding together well. After being washed away by rainwater, it became loose and weak, causing soil erosion and poor subsequent repair effect.

[0087] Test Example 2 The environmental remediation soil particles prepared in Examples 1-10 and Comparative Examples 1-5 were tested. The test method was as follows: the environmental remediation soil particles of Examples 1-10 and Comparative Examples 1-5 were applied to the slope surface of a highway, for a total of 15 groups, with each group having the same experimental area; the application rate of the environmental remediation soil particles was 200 kg / m². 2 The soil thickness is 8-12 cm; Bahia grass is planted 3 days after the application of environmental remediation soil granules, with a seeding rate of 20 g / m². 2 The observation period was 360 days, and soil coverage and vegetation coverage were recorded. Soil coverage refers to the proportion of soil area with a thickness greater than 2 cm in each group to the total area of ​​that group; vegetation coverage refers to the proportion of plant-covered area in each group to the area covered by environmental remediation soil particles in that group. The results are shown in Table 2 and... Figure 1 As shown.

[0088] Table 2 Test results of Examples 1-10 and Comparative Examples 1-5

[0089] According to Table 2 and Figure 1 As can be seen, the hydrogel-based curing agent provided by this invention can significantly improve the adhesion performance of soil, enabling the environmental remediation soil particles provided by this invention to better adhere to the remediated surface, thereby improving the remediation effectiveness. Furthermore, the particles remain well-adhered even after 360 days, indicating that the environmental remediation soil particles provided by this invention have a good long-term mechanism, significantly improving the long-term effectiveness of soil remediation. In addition, the environmental remediation soil particles provided by this invention can provide good fertility and moisture content for plant growth. By absorbing and holding water during periods of abundant rainfall and releasing water during periods of scarce rainfall, it ensures a relatively stable plant growth environment and improves plant survival rates. Through the above mechanisms, this invention achieves a relatively ideal final effect in soil remediation, realizing the goals of soil remediation and vegetation greening, with significant economic and social benefits.

[0090] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the above embodiments of the present invention without inventive effort are within the protection scope of the present invention.

Claims

1. A hydrogel-based curing agent, characterized in that, The raw materials include the following parts by weight: 8-15 parts sodium alginate, 3-8 parts chitosan, 1-3 parts acetic acid, 2-6 parts calcium chloride, 4-10 parts nano-bentonite, 0.5-2 parts polyglutamic acid, and 50-80 parts water.

2. The hydrogel-based curing agent according to claim 1, characterized in that, The sodium alginate contains 72-83% mannuronic acid.

3. The hydrogel-based curing agent according to claim 1, characterized in that, The nano-bentonite includes first nano-bentonite and second nano-bentonite. The particle size of the first nano-bentonite is 20~60 nanometers; The particle size of the second nano-bentonite is 70-80 nanometers.

4. The hydrogel-based curing agent according to claim 3, characterized in that, The mass ratio of the first nano-bentonite to the second nano-bentonite is 100:20~35.

5. The hydrogel-based curing agent according to claim 1, characterized in that, The polyglutamic acid has a number-average molecular weight of 70,000 to 120,000 Da.

6. A method for preparing the hydrogel-based curing agent according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Sodium alginate, water, nano-bentonite, chitosan, acetic acid and calcium chloride were mixed and subjected to ionic cross-linking reaction to obtain hydrogel complex; (2) The hydrogel complex and polyglutamic acid are mixed to obtain the hydrogel-based curing agent.

7. The application of the hydrogel-based curing agent according to any one of claims 1 to 5 or the hydrogel-based curing agent obtained by the preparation method according to claim 6 in the field of environmental remediation.

8. An environmental remediation soil particle, characterized in that, The components include the following parts by mass: 100 parts red clay, 5-10 parts bamboo shavings, 3-6 parts tea seed husks, 5-7 parts animal manure, 15-25 parts hydrogel-based curing agent and 20-30 parts water; The hydrogel-based curing agent is the hydrogel-based curing agent according to any one of claims 1 to 5 or the hydrogel-based curing agent obtained by the preparation method according to claim 6.

9. The environmental remediation soil particles according to claim 8, characterized in that, The particle size of the environmental remediation soil particles is 2-5 mm.

10. The method for preparing environmental remediation soil particles according to any one of claims 8 to 9, characterized in that, Includes the following steps: Red clay, bamboo shavings, tea seed shells, animal manure, hydrogel-based curing agent, and water are mixed and granulated in a drum to obtain the environmental remediation soil particles.

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