Preparation method of algae-based high-water-absorption gel soil conditioner

Abstract

The preparation method of the algae-based high-water-absorption gel soil conditioner takes algae as a raw material, the algae and a grafting monomer are subjected to graft polymerization to obtain the algae-based high-water-absorption gel soil conditioner, and the preparation method specifically comprises the following steps: treating the algae, and uniformly stirring and mixing the treated algae in water to obtain algae slurry; preparing a grafting monomer into a solution for later use; adding a cross-linking agent, an initiator and a grafting monomer into the algae slurry, and carrying out graft polymerization reaction to obtain a crude product; the crude product is subjected to impurity removal, drying and smashing, and the algae-based high-water-absorption gel soil conditioner is prepared. According to the method, synthesis of the super absorbent gel soil conditioner is completed through aqueous solution graft polymerization, no waste or pollutant is generated in the whole process, the environmental protection problems of organic solvent volatilization, by-product emission and the like in a traditional process are avoided, and clean production is achieved; the prepared algae-based high-water-absorption gel soil conditioner has excellent water retention performance, remarkable soil improvement effect and biodegradability, and has good application prospects in the fields of agriculture, environmental protection, ecological restoration and the like.

Description

Technical Field

[0001] This invention relates to a method for preparing an algae-based superabsorbent resin soil conditioner, specifically belonging to the field of agricultural and environmental protection technology. Background Technology

[0002] Soil conditioners, represented by superabsorbent polymers (SAPs), are three-dimensional network polymer materials capable of absorbing and locking in large amounts of water, playing a significant role in agricultural drought resistance, sand fixation, and grass cultivation. However, traditional petroleum-based resins suffer from problems such as non-renewable raw materials, difficulty in degradation, and high carbon emissions, limiting their large-scale ecological application. Therefore, the synthesis of biodegradable superabsorbent gel soil conditioners from natural and inexpensive raw materials has become a research hotspot in this field.

[0003] my country boasts abundant algal resources, with macroalgae such as Spirogyra and microalgae widely distributed in natural water bodies, representing biological resources of significant development value. These algal cells are rich in natural macromolecules such as polysaccharides and proteins, and their molecular structures contain numerous active groups. They can be used directly as polymeric frameworks or modified through grafting to construct three-dimensional network structures, making them ideal raw materials for preparing superabsorbent polymer (SAP) soil conditioners. Traditional algal treatment methods, such as harvesting, landfilling, and incineration, are not only costly but also wasteful of resources. Using algae as raw materials to prepare SAP not only achieves high-value utilization of biomass resources but also significantly reduces production costs while endowing the material with excellent biodegradability. Currently, research on converting algal biomass into polymers for soil improvement has not been reported. Summary of the Invention

[0004] This invention provides a method for preparing an algae-based superabsorbent gel soil conditioner, resulting in a simple, readily available, low-cost, and high-performance superabsorbent gel soil conditioner made from algae.

[0005] This invention discloses a method for preparing an algae-based superabsorbent polymer soil conditioner, characterized in that: the preparation method uses algae as raw material, and performs graft polymerization with graft monomers to obtain the algae-based superabsorbent polymer soil conditioner. The specific steps are as follows: Step 1: Pre-treat the algae raw material to obtain the algae treated product; Step 2: Mix the grafted monomer and water to form a monomer solution and place it in an ice-water bath to prevent self-polymerization; wherein, the mass ratio of grafted monomer to water is 0.1-0.9:1. Step 3: Mix the algae treatment material and water at 10-90℃ and a stirring speed of 100-3000 r / min to form an algae slurry; wherein the mass ratio of dry algae to water in the algae treatment material is 0.01-0.9:1. Step 4: Add the initiator, monomer solution, and crosslinking agent sequentially to the algal slurry and stir to mix. Stir at 10-90℃ and 100-3000 r / min until a gel-like viscous mass appears, then stop stirring and continue the reaction for 2-3 hours to obtain the crude product. The mass ratio of algal slurry, initiator, grafted monomer, crosslinking agent, and water is 1-10:0.01-0.1:0.1-0.9:0.001-0.1:1. Step 5: Cut the crude product into small pieces with scissors, wash it 3-4 times with deionized water, soak it in anhydrous ethanol for 24-36 hours to remove impurities, and then dry it continuously at 60℃ to constant weight. After cooling, crush and sieve to obtain algae-based superabsorbent gel soil conditioner.

[0006] The algae raw materials mentioned are any one or a combination of several of Spirogyra, Bambusa textilis, Deer Antler Seaweed, Kelp, Wakame seaweed, Sargassum, Bulbae, Porphyra, Gracilaria, Euphorbia lathyris, Ulva, Cladosporium, Spirulina, Chlorella, Scenedesmus, and Anabaena, and are fresh algae with a water content ≥60% or dried algae powder.

[0007] The pretreatment is as follows: homogenization of fresh algae or mechanical crushing of algae powder to achieve a particle size of 0.250-0.0450 mm for the algae treatment.

[0008] The grafting monomers include any one or a combination of several of the following: acrylic acid, butyl acrylate, acrylamide, methyl acrylate, methacrylic acid, methyl methacrylate, hydroxyethyl methacrylate, maleic acid, maleic anhydride, diethyl maleate, dibutyl maleate, diisopropyl maleate, low-coupling maleic acid ester, p-phenylenediamine bismaleic acid, vinyltrimethoxysilane, vinyltriethoxysilane, itaconic acid, vinyl alcohol, polyvinyl alcohol, and acrylonitrile.

[0009] The initiator is any one or a combination of several of the following: potassium persulfate, sodium persulfate, ammonium persulfate, triethyl or tri-n-butyl or triisobutylboron, cerium ammonium nitrate, cerium sulfate, cerium acetate, hydrogen peroxide, and urea peroxide.

[0010] The crosslinking agent is one or a combination of several of the following: N,N'-methylenebisacrylamide, aluminum hydroxide, polyethylene glycol, glycerol, sodium citrate, tetraethylene glycol diacrylate, divinyl sulfone, glutaraldehyde, epichlorohydrin, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, borax, and polyethylene glycol diglycidyl ether.

[0011] The beneficial effects of this invention are as follows: 1. Using algae as the core raw material, it replaces traditional fossil energy-based materials, reducing dependence on non-renewable resources. Algae can be obtained through large-scale cultivation (such as Spirulina, Chlorella, etc.) or wild harvesting (such as Spirogyra, Cladosporium, etc.), realizing the effective utilization of natural resources. At the same time, the finished algae-based superabsorbent gel soil conditioner has biodegradable properties and can be naturally degraded after use. 2. The superabsorbent gel soil conditioner is synthesized by graft polymerization of aqueous solution, with no waste or pollutants generated throughout the process. It avoids environmental problems such as the volatilization of organic solvents and the emission of by-products in traditional processes, and realizes clean production. Attached Figure Description

[0012] Figure 1 This is a process flow diagram for preparing the algae-based superabsorbent gel soil conditioner of the present invention; Figure 2 shows the appearance morphology of the algae-based superabsorbent gel soil conditioner of the present invention before water absorption and swelling. Figure 2-2 This is a morphological image of the algae-based superabsorbent gel soil conditioner after it has absorbed water and swelled. Figure 3 This invention relates to changes in soil porosity after application of the algae-based superabsorbent gel soil conditioner. Detailed Implementation

[0014] Example 1 Fresh spirulina algae were dried in an oven at 60℃ to constant weight and then pulverized in a pulverizer to obtain spirulina dry powder with a particle size of less than 0.15 mm. After the grafted monomer acrylic acid and water were mixed, the mixture was placed in an ice-water bath to prevent self-polymerization, and a 20 wt% sodium hydroxide solution was added for neutralization reaction. The mass of acrylic acid, sodium hydroxide and water were 8 g, 3.2 g and 20 g, respectively. Spirulina powder and water were stirred at 50°C and 600 r / min for 3 hours to form a spirulina paste, wherein the mass of spirulina powder and water was 10 g and 50 g, respectively. Spirulina slurry was mixed with potassium persulfate initiator, acrylic acid graft monomer, N,N'-methylenebisacrylamide crosslinking agent, and water in sequence. The mixture was stirred at 70°C and 300 r / min for 2 hours. Stirring was stopped when a gel-like viscous mass appeared. The reaction was continued for 3 hours to obtain the crude product. The mass of spirulina slurry, initiator, graft monomer, crosslinking agent, and water were 60 g, 0.49 g, 8 g, 0.2 g, and 40 g, respectively. The crude product was cut into small pieces with scissors, washed three times with deionized water, and then soaked in anhydrous ethanol for 36 hours to remove water and impurities. The product was then dried continuously at 60°C for 24 hours until constant weight. After cooling, it was pulverized and sieved to obtain algae-based superabsorbent gel soil conditioner.

[0015] Example 2 Spirulina fresh algae with a water content of 90% were stirred in a mixer to form a spirulina fresh algae homogenate with a particle size of less than 0.15 mm. After the grafted monomer acrylic acid and water were mixed, the mixture was placed in an ice-water bath to prevent self-polymerization, and a 20 wt% sodium hydroxide solution was added for neutralization reaction; the mass of acrylic acid, sodium hydroxide and water were 17.6 g, 7.04 g and 20 g, respectively. The fresh spirulina homogenate and water were stirred at 50°C and 600 r / min for 3 hours to form a spirulina paste, wherein the dry spirulina and water weighed 10 g and 100 g respectively. Spirulina slurry was mixed with potassium persulfate initiator, acrylic acid graft monomer, N,N'-methylenebisacrylamide crosslinking agent, and water in sequence. The mixture was stirred at 70°C and 300 r / min for 2 hours. Stirring was stopped when a gel-like viscous mass appeared. The reaction was continued for 3 hours to obtain the crude product. The mass ratios of spirulina slurry, initiator, graft monomer, crosslinking agent, and water were 110 g, 1.012 g, 17.6 g, 0.44 g, and 44 g, respectively. The crude product was cut into small pieces with scissors, washed three times with deionized water, and then soaked in anhydrous ethanol for 36 hours to remove water and impurities. The product was then dried continuously at 60°C for 24 hours until constant weight. After cooling, it was pulverized and sieved to obtain algae-based superabsorbent gel soil conditioner.

[0016] Example 3 The collected wakame seaweed was dried in an oven at 60℃ to constant weight and then pulverized in a pulverizer to obtain wakame seaweed powder with a particle size of less than 0.15 mm. After the grafted monomer acrylic acid and water were mixed, the mixture was placed in an ice-water bath to prevent self-polymerization, and a 20 wt% sodium hydroxide solution was added for neutralization reaction; the mass of acrylic acid, sodium hydroxide and water were 8 g, 3.2 g and 20 g, respectively. The dried wakame seaweed powder and water were stirred at 50°C and 600 r / min for 3 hours to form a wakame seaweed paste; the mass ratio of dried wakame seaweed powder to water was 10 g and 50 g. The wakame seaweed slurry was mixed with potassium persulfate initiator, acrylic acid graft monomer, N,N'-methylenebisacrylamide crosslinking agent, and water in sequence. The mixture was stirred at 70°C and 300 r / min for 2 hours. Stirring was stopped when a gel-like viscous mass appeared. The reaction was continued for 3 hours to obtain the crude product. The mass ratio of wakame seaweed slurry, initiator, graft monomer, crosslinking agent, and water was 60 g, 0.49 g, 8 g, 0.2 g, and 40 g, respectively. The crude product was cut into small pieces with scissors, washed three times with deionized water, and then soaked in anhydrous ethanol for 36 hours to remove water and impurities. The product was then dried continuously at 60°C for 24 hours until constant weight. After cooling, it was pulverized and sieved to obtain algae-based superabsorbent gel soil conditioner.

[0017] Test case The following performance tests were conducted on the algae-based superabsorbent gel soil conditioners prepared in Examples 1-3 of this invention: 1. Swelling performance test A certain weight of alkali-based superabsorbent polymer soil conditioner was soaked in excess water until saturation. The swollen superabsorbent polymer was then filtered and separated. The swelling ratio Qeq (g / g) of the alkali-based superabsorbent polymer soil conditioner was calculated using the formula: ; Where M1(g) and M2(g) are the weights of the dry sample and the water-swelled sample, respectively, and Qeq (g / g) represents the grams of water contained per gram of sample. The changes in swelling morphology are shown in Figure 2, and the experimental results are shown in Table 1. ; 2. Soil water holding capacity test 0 wt% and 1 wt% of the algae-based superabsorbent gel soil conditioner from Examples 1-3 were added to the predetermined soil mass, respectively. After two cycles of water absorption, the soil was placed in a ventilated environment for 7 days to incubate. Soil samples were then immersed in tap water to ensure full absorption, excess water was drained, and the samples were weighed. Changes in soil morphology before and after application are shown in the figure. Figure 3 As shown. The method for calculating soil water holding capacity (SWHR) is as follows: ; M0(g) and M1(g) are the weights of dry and wet soil, respectively. The test results are shown in Table 2. ; from Figure 3It can be seen that alkali-based superabsorbent polymers (SAPs) can effectively enhance the soil's pore structure, which is significant for improving the soil's water retention capacity. Simultaneously, soil improved with SAPs retains a large amount of water that is difficult for plants to access, thus greatly improving plant water use efficiency. Adding SAPs to soil can significantly improve its water-holding capacity, ensure stable water supply, and reduce water waste, which is crucial for agriculture in arid regions.

Claims

1. A method for preparing an algae-based superabsorbent gel soil conditioner, characterized in that: The preparation method uses algae as raw material and performs graft polymerization with graft monomers to obtain an algae-based superabsorbent polymer soil conditioner. The specific steps are as follows: Step 1: Pre-treat the algae raw material to obtain the algae treated product; Step 2: Mix the grafted monomer and water to form a monomer solution and place it in an ice-water bath to prevent self-polymerization; wherein, the mass ratio of grafted monomer to water is 0.1-0.9:

1. Step 3: Mix the algae treatment material and water at 10-90℃ and a stirring speed of 100-3000 r / min to form an algae slurry; wherein the mass ratio of dry algae to water in the algae treatment material is 0.01-0.9:

1. Step 4: Add the initiator, monomer solution, and crosslinking agent sequentially to the algal slurry and stir to mix. Stir at 10-90℃ and 100-3000 r / min until a gel-like viscous mass appears, then stop stirring and continue the reaction for 2-3 hours to obtain the crude product. The mass ratio of algal slurry, initiator, grafted monomer, crosslinking agent, and water is 1-10:0.01-0.1:0.1-0.9:0.001-0.1:

1. Step 5: Cut the crude product into small pieces with scissors, wash it 3-4 times with deionized water, soak it in anhydrous ethanol for 24-36 hours to remove impurities, and then dry it continuously at 60℃ to constant weight. After cooling, crush and sieve to obtain algae-based superabsorbent gel soil conditioner.

2. The method for preparing an algae-based superabsorbent gel soil conditioner according to claim 1, characterized in that: The algae raw materials mentioned are any one or a combination of several of Spirogyra, Bambusa textilis, Deer Antler Seaweed, Kelp, Wakame seaweed, Sargassum, Bulbae, Porphyra, Gracilaria, Euphorbia lathyris, Ulva, Cladosporium, Spirulina, Chlorella, Scenedesmus, and Anabaena, and are fresh algae with a water content ≥60% or dried algae powder.

3. The method for preparing an algae-based superabsorbent gel soil conditioner according to claim 1, characterized in that: The pretreatment is as follows: homogenization of fresh algae or mechanical crushing of algae powder to achieve a particle size of 0.250-0.0450 mm for the algae treatment.

4. The method for preparing an algae-based superabsorbent gel soil conditioner according to claim 1, characterized in that: The grafting monomers include any one or a combination of several of the following: acrylic acid, butyl acrylate, acrylamide, methyl acrylate, methacrylic acid, methyl methacrylate, hydroxyethyl methacrylate, maleic acid, maleic anhydride, diethyl maleate, dibutyl maleate, diisopropyl maleate, low-coupling maleic acid ester, p-phenylenediamine bismaleic acid, vinyltrimethoxysilane, vinyltriethoxysilane, itaconic acid, vinyl alcohol, polyvinyl alcohol, and acrylonitrile.

5. The method for preparing an algae-based super absorbent soil conditioner according to claim 1, characterized in that: The initiator is any one or a combination of several of the following: potassium persulfate, sodium persulfate, ammonium persulfate, triethyl or tri-n-butyl or triisobutylboron, cerium ammonium nitrate, cerium sulfate, cerium acetate, hydrogen peroxide, and urea peroxide.

6. The method for preparing an algae-based superabsorbent gel soil conditioner according to claim 1, characterized in that: The crosslinking agent is one or a combination of several of the following: N,N'-methylenebisacrylamide, aluminum hydroxide, polyethylene glycol, glycerol, sodium citrate, tetraethylene glycol diacrylate, divinyl sulfone, glutaraldehyde, epichlorohydrin, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, borax, and polyethylene glycol diglycidyl ether.

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