A straw fiber adsorption material for ecological restoration spraying

Abstract

The invention discloses a straw fiber adsorption material for ecological restoration spray seeding, belongs to the technical field of ecological restoration, and is prepared by the following steps: S1, mixing a Tris-HCl buffer with a pH of 8.5 with anhydrous ethanol, then adding dopamine hydrochloride, a terminal thiol hyperbranched polyester, and pretreated straw fibers, stirring and reacting at 30°C for 12 hours, filtering, washing the filter cake, and drying to obtain an intermediate product; S2, placing the intermediate product in deionized water, adding chloroacetic acid, stirring and reacting at 70-80°C for 8-10 hours, filtering, washing the filter cake, and drying to obtain the straw fiber adsorption material for ecological restoration spray seeding, applying the straw fiber adsorption material to a spray seeding matrix to absorb moisture, thereby providing sufficient moisture for plant growth, and having antibacterial properties, so as not to be quickly eroded and decomposed by bacteria in the soil, and being able to effectively play a skeleton role. The straw fiber adsorption material has a prominent effect on ore slopes or soil contaminated by heavy metal ions.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration, and in particular relates to a straw fiber adsorption material for ecological restoration spraying. Background Art

[0002] With the rapid development of ecological construction and increased investment, people's awareness of environmental protection has gradually increased. Spray greening technology has been widely used in slope ecological protection and vegetation restoration projects formed by transportation, hydropower, mining, municipal and other engineering construction projects, playing a significant role in protecting slopes and restoring vegetation.

[0003] The existing spraying matrix generally includes soil, plant fiber, adhesive, grass seeds and other components. The main functions of plant fiber are: 1) covering the surface soil, forming a thick, uniform and dense fiber covering layer on the surface of the topsoil to prevent wind and rain from eroding the surface soil; 2) improving the soil structure. The slope surface after spraying plant fiber can absorb a large amount of dust particles, making the particles of powdery soil larger. The fibers are interwoven to form a nesting structure skeleton, which is beneficial to the stability of the aggregates; 3) conserving water. Plant fiber has a certain water absorption capacity, which can prolong the soil moistening period, Plant growth requires sufficient water; crop straw, as a green and environmentally friendly biomass resource, has the advantage of a wide source, and using it to prepare plant fibers in spray-seeding matrices has great development prospects. However, the straw raw material has a smooth surface and contains ash, wax, and sugar, which makes it have poor interfacial bonding with binders and other substances. In addition, it has low hydrophilicity and no antibacterial properties, making it difficult to retain water. At the same time, it is easily decomposed by microorganisms and bacteria in the soil, making it difficult to effectively play a skeleton role. Therefore, it is necessary to provide a straw fiber adsorption material for spray-seeding with high hydrophilicity and antibacterial properties for ecological restoration. Summary of the Invention

[0004] The purpose of the present invention is to provide a straw fiber adsorption material for ecological restoration spray seeding, so as to solve the technical problem that the existing straw fiber has low hydrophilicity, no antibacterial property and is not suitable for use as fiber for ecological restoration spray seeding.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A straw fiber adsorption material for ecological restoration spraying is made by the following steps:

[0007] S1. Mixing Tris-HCl buffer with a pH of 8.5 with anhydrous ethanol, then adding dopamine hydrochloride, thiol-terminated hyperbranched polyester, and pretreated straw fiber, stirring at 30°C for 12 hours, filtering, rinsing the filter cake with deionized water 4-5 times, and finally drying it with air at 60°C to obtain an intermediate product;

[0008] S2. Place the intermediate product in deionized water, add chloroacetic acid, and react at 70-80°C with stirring for 8-10 hours. After the reaction is completed, filter, rinse the filter cake with deionized water 4-5 times, and finally place it at 60°C for air drying to obtain the straw fiber adsorption material for ecological restoration spraying.

[0009] As a preferred technical solution of the present invention, the usage ratio of Tris-HCl buffer, anhydrous ethanol, dopamine hydrochloride, thiol-terminated hyperbranched polyester and pretreated straw fiber in S1 is 20-30 mL: 20-30 mL: 0.16-0.20 g: 0.085-0.1 g: 3-4 g.

[0010] As a preferred technical solution of the present invention, the usage ratio of the intermediate product, deionized water and chloroacetic acid in S2 is 3-4 g: 40-60 mL: 0.3-0.6 g.

[0011] As a preferred technical solution of the present invention, the thiol-terminated hyperbranched polyester is prepared by the following steps:

[0012] Triethanolamine, 4-mercaptopyridinedicarboxylic acid, p-toluenesulfonic acid and DMF were added to a flask. Under nitrogen protection, the temperature was raised to 130°C with magnetic stirring and the reaction was continued at this temperature for 2 hours. The temperature was then raised to 150°C and vacuumed and the reaction was continued for 2 hours. After the reaction was completed, the DMF was removed by rotary evaporation to obtain a thiol-terminated hyperbranched polyester.

[0013] The molar ratio of triethanolamine to 4-mercaptopyridine dicarboxylic acid is 1:1, the amount of p-toluenesulfonic acid used is 2-3% of the mass of the total of triethanolamine and 4-mercaptopyridine dicarboxylic acid, 4-mercaptopyridine dicarboxylic acid is used as an A2-type monomer, A is a carboxyl group, triethanolamine is used as a B3-type monomer, and B is a hydroxyl group. A terminal mercapto hyperbranched polyester containing structures such as a pyridine ring, a tertiary amine, and hydroxyl and carboxyl groups is prepared through the A2+B3 system.

[0014] As a preferred technical solution of the present invention, the pretreated straw fiber is prepared by the following steps:

[0015] The husk and pith of corn stalks are separated by a husk and pith separator, the separated husk is washed with water, dried, crushed, passed through a 20-mesh sieve, and ground in a grinder for 3-5 minutes to obtain corn stalk fibers, the corn stalk fibers are transferred to a 0.5-1.5wt% sodium hypochlorite solution, soaked at 70-80°C for 50-70 minutes, filtered, and the filter cake is rinsed with deionized water and dried;

[0016] Among them, the usage ratio of corn straw fiber and sodium hypochlorite solution is 1-2g:10mL. Sodium hypochlorite is used to treat the corn straw fiber to remove smooth surfaces such as pectin and wax on its surface, making the surface of the straw fiber rough and the internal gaps larger, thereby increasing the water absorption rate of the straw fiber.

[0017] Beneficial effects of the present invention:

[0018] The invention provides a straw fiber adsorption material for ecological restoration spray seeding. The straw fiber is first treated with a sodium hypochlorite solution to remove smooth surfaces such as pectin and wax on the surface, increase the surface roughness and porosity, and improve the interface bonding between the straw fiber and other materials. Then, a dopamine oxidative self-polymerization reaction is used to form a polydopamine coating layer on the surface of the pretreated straw fiber, and catechol and amino active groups are introduced to obtain an intermediate product. The catechol structure can form a strong hydrogen bond with the surfaces of different objects and has a metal chelation effect. The amino active group can trigger a Michael addition reaction with the thiol group of the terminal thiol hyperbranched polyester. A thioether structure is introduced on the surface of the intermediate product to form a polymer coating. The polymer coating contains a plurality of pyridine rings, tertiary amines, hydroxyl groups, carboxyl groups and other structures. The hydroxyl groups and carboxyl groups are hydrophilic groups and can give the straw fiber excellent hydrophilic properties. The pyridine rings and tertiary amines can react with chloroacetic acid to form a strong hydrogen bond. The quaternary ammonium salt structure is formed to give the straw fiber good antibacterial properties. Therefore, the straw fiber adsorption material obtained by the present invention not only has excellent hydrophilicity, but also has good antibacterial properties. In addition, its surface also contains numerous structures such as catechol, amino group, thioether bond, etc., which have good chelating properties for heavy metal ions, and can give the straw fiber excellent adsorption properties for heavy metal ions. In summary, the straw fiber adsorption material is applied to the spraying matrix, which can not only cover the surface soil, prevent wind and rain from eroding the soil, absorb moisture, and provide sufficient moisture for plant growth, but also has antibacterial properties, will not be quickly eroded and decomposed by bacteria in the soil, can effectively play a skeleton role, and has an outstanding effect on ore slopes or soil contaminated by heavy metal ions, specifically manifested in stabilizing heavy metal ions through adsorption, reducing the penetration and migration of heavy metal ions, and is beneficial to the health of humans and animals. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0020] Example 1

[0021] A thiol-terminated hyperbranched polyester is prepared by the following steps:

[0022] 0.1 mol of triethanolamine, 0.1 mol of 4-mercaptopyridinedicarboxylic acid, 0.7 g of p-toluenesulfonic acid and 400 mL of DMF were added to a flask. Under nitrogen protection, the temperature was raised to 130°C with magnetic stirring and the reaction was carried out at a constant temperature for 2 hours. The temperature was further raised to 150°C, vacuumed, and the reaction was carried out for 2 hours. After the reaction was completed, DMF was removed by rotary evaporation to obtain a terminal thiol hyperbranched polyester.

[0023] Example 2

[0024] A thiol-terminated hyperbranched polyester is prepared by the following steps:

[0025] 0.1 mol of triethanolamine, 0.1 mol of 4-mercaptopyridinedicarboxylic acid, 1.0 g of p-toluenesulfonic acid and 500 mL of DMF were added to a flask. Under nitrogen protection, the temperature was raised to 130°C with magnetic stirring and the reaction was carried out at a constant temperature for 2 hours. The temperature was further raised to 150°C, vacuumed, and the reaction was carried out for 2 hours. After the reaction was completed, DMF was removed by rotary evaporation to obtain a terminal thiol hyperbranched polyester.

[0026] Example 3

[0027] A straw fiber adsorption material for ecological restoration spraying is made by the following steps:

[0028] S1, 20L of Tris-HCl buffer with a pH of 8.5 was mixed with 20L of anhydrous ethanol, followed by the addition of 0.16kg of dopamine hydrochloride, 0.085kg of the thiol-terminated hyperbranched polyester of Example 1, and 3kg of pretreated straw fiber. The mixture was stirred at 30°C for 12h, and then filtered. The filter cake was rinsed four times with deionized water, and finally dried under forced air at 60°C to obtain an intermediate product.

[0029] S2. Place 3 kg of the intermediate product in 40 L of deionized water, add 0.3 kg of chloroacetic acid, and stir the reaction at 70 ° C for 8 hours. After the reaction is completed, filter, rinse the filter cake with deionized water 4 times, and finally place it at 60 ° C for forced air drying to obtain the straw fiber adsorption material for ecological restoration spraying.

[0030] The pretreated straw fibers are prepared by the following steps:

[0031] The husk and pith of corn stalks were separated using a husk and pith separator, the separated husk was washed and dried with water, crushed and passed through a 20-mesh sieve, and ground in a grinder for 3 minutes to obtain corn stalk fiber. 10 kg of corn stalk fiber was transferred to 100 L of 0.5 wt% sodium hypochlorite solution, soaked at 70°C for 50 minutes, filtered, and the filter cake was rinsed with deionized water and dried.

[0032] Example 4

[0033] A straw fiber adsorption material for ecological restoration spraying is made by the following steps:

[0034] S1, 25L of Tris-HCl buffer with a pH of 8.5 was mixed with 25L of anhydrous ethanol, followed by the addition of 0.18kg of dopamine hydrochloride, 0.09kg of the thiol-terminated hyperbranched polyester of Example 2, and 3.5kg of pretreated straw fiber. The mixture was stirred at 30°C for 12h, filtered, and the filter cake was rinsed four times with deionized water, and finally dried under forced air at 60°C to obtain an intermediate product;

[0035] S2. Place 3.5 kg of the intermediate product in 50 L of deionized water, add 0.4 kg of chloroacetic acid, and stir the reaction at 75 ° C for 9 hours. After the reaction is completed, filter, rinse the filter cake with deionized water 4 times, and finally place it at 60 ° C for air drying to obtain the straw fiber adsorption material for ecological restoration spraying.

[0036] The pretreated straw fibers are prepared by the following steps:

[0037] The husk and pith of corn stalks were separated using a husk and pith separator, the separated husk was washed and dried with water, crushed and passed through a 20-mesh sieve, and ground in a grinder for 4 minutes to obtain corn stalk fiber. 15 kg of corn stalk fiber was transferred to 100 L of 1 wt% sodium hypochlorite solution, soaked at 75°C for 60 minutes, filtered, and the filter cake was rinsed with deionized water and dried.

[0038] Example 5

[0039] A straw fiber adsorption material for ecological restoration spraying is made by the following steps:

[0040] S1, 30L of Tris-HCl buffer with a pH of 8.5 was mixed with 30L of anhydrous ethanol, followed by the addition of 0.20kg of dopamine hydrochloride, 0.1kg of the thiol-terminated hyperbranched polyester of Example 2, and 4kg of pretreated straw fiber. The mixture was stirred at 30°C for 12h, filtered, and the filter cake was rinsed with deionized water 5 times, and finally dried under forced air at 60°C to obtain an intermediate product;

[0041] S2. Place 4 kg of the intermediate product in 60 L of deionized water, add 0.6 kg of chloroacetic acid, and stir the reaction at 80 ° C for 10 hours. After the reaction is completed, filter, rinse the filter cake with deionized water 5 times, and finally place it at 60 ° C for forced air drying to obtain the straw fiber adsorption material for ecological restoration spraying.

[0042] The pretreated straw fibers are prepared by the following steps:

[0043] The husk and pith of corn stalks were separated using a husk and pith separator, the separated husk was washed and dried with water, crushed and passed through a 20-mesh sieve, and ground in a grinder for 5 minutes to obtain corn stalk fiber. 20 kg of corn stalk fiber was transferred to 100 L of 1.5 wt% sodium hypochlorite solution, soaked at 80°C for 70 minutes, filtered, and the filter cake was rinsed with deionized water and dried.

[0044] Comparative Example 1

[0045] Compared with Example 3, on the basis of Example 3, only the terminal mercapto hyperbranched polyester in Example 3 is replaced with 4-mercaptopyridinedicarboxylic acid, and the remaining raw materials and preparation process are the same as Example 3.

[0046] Comparative Example 2

[0047] This comparative example is the intermediate product obtained in step S1 of Example 3.

[0048] The straw fiber adsorption materials obtained in Examples 3 to 5 and Comparative Examples 1 and 2 were tested, and the test items were as follows:

[0049] (1) Contact angle test

[0050] The contact angles of the samples of Examples 3 to 5 and Comparative Examples 1 and 2 were measured using a JC2000D1 contact angle meter at room temperature using deionized water drops on the surface of the dried samples. Each group of samples was measured at least four times at different locations, with a spacing of ≥15 mm between each two measurements, and the results were averaged.

[0051] (2) Antibacterial test: Escherichia coli was selected as a representative of Gram-negative bacteria, and Staphylococcus aureus was selected as a representative of Gram-positive bacteria. According to the provisions of "GB / T 20944.3-2088 Evaluation of Antibacterial Properties of Textiles", the antibacterial rates of the samples of Examples 3 to 5 and Comparative Examples 1 and 2 against Escherichia coli and Staphylococcus aureus were tested and calculated as percentages;

[0052] (III) Heavy Metal Ion Adsorption Test: 0.1 g of each sample from Examples 3 to 5 and Comparative Examples 1 and 2 was taken, and at pH 9, a volume of 100 mL and a concentration of 50 mg / L of Pb(II) and Cd(II) were statically adsorbed under stirring with a magnetic stirrer. The Pb(II) and Cd(II) removal rates were calculated.

[0053] The results are shown in Table 1:

[0054] Table 1

[0055] project Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Contact angle (°) 45.3 41.4 43.6 49.2 47.8 Antibacterial rate of Escherichia coli (%) 97.0 98.4 97.2 82.1 68.4 Antibacterial rate of Staphylococcus aureus (%) 95.1 96.2 95.7 80.5 65.2 Pb(II) removal rate (%) 98.4 99.3 99.1 94.2 98.3 Cd(II) removal rate (%) 99.6 99.8 99.7 93.1 99.4

[0056] As can be seen from Table 1, compared with Comparative Example 1 and Comparative Example 2, the straw fiber adsorption materials obtained in Example 3, Example 4, and Example 5 have good hydrophilicity, antibacterial property and heavy metal adsorption performance. Specifically, the straw fiber adsorption material obtained in Comparative Example 1 is compared with Example 3. Since the terminal thiol hyperbranched polyester is replaced with 4-mercaptopyridine dicarboxylic acid, the surface modification layer of the obtained intermediate product lacks the characteristics of the hyperbranched polymer (three-dimensional cavities, numerous hydrophilic groups, and tertiary amine structures), resulting in the obtained product having significantly worse hydrophilicity, antibacterial property and heavy metal ion adsorption performance. Compared with Example 3, the straw fiber adsorption material obtained in Comparative Example 2 did not undergo the quaternary ammonium chloroacetate step, and could not introduce the quaternary ammonium salt structure and the hydrophilic carboxyl group, resulting in the obtained product having significantly worse hydrophilicity and antibacterial property. In summary, the straw fiber adsorption material prepared by the present invention has good hydrophilicity, antibacterial property and heavy metal adsorption performance, and has great application value in the ecological restoration spraying matrix.

[0057] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0058] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A straw fiber adsorption material for ecological restoration spraying, characterized in that: Made by the following steps: S1. Mixing Tris-HCl buffer with a pH of 8.5 with anhydrous ethanol, then adding dopamine hydrochloride, thiol-terminated hyperbranched polyester, and pretreated straw fiber, stirring at 30° C. for 12 h, filtering, washing the filter cake, and drying to obtain an intermediate product; S2. placing the intermediate product in deionized water, adding chloroacetic acid, stirring and reacting at 70-80° C. for 8-10 hours, filtering, washing the filter cake, and drying to obtain a straw fiber adsorption material for ecological restoration spraying; The mercapto-terminated hyperbranched polyester is prepared by the following steps: Triethanolamine, 4-mercaptopyridinedicarboxylic acid, p-toluenesulfonic acid and DMF were added to a flask. Under nitrogen protection, the temperature was raised to 130°C with magnetic stirring and the reaction was continued at this temperature for 2 hours. The temperature was then raised to 150°C and vacuumed and the reaction was continued for 2 hours. After the reaction was completed, the DMF was removed by rotary evaporation to obtain a thiol-terminated hyperbranched polyester. Pretreated straw fiber is made through the following steps: The husk and pith of corn stalks are separated by a husk and pith separator, the separated husk is washed and dried with water, crushed and passed through a 20-mesh sieve, and ground in a grinder for 3-5 minutes to obtain corn stalk fibers, which are then transferred to a sodium hypochlorite solution, soaked at 70-80° C. for 50-70 minutes, filtered, and the filter cake is rinsed with deionized water and dried.

2. The straw fiber adsorption material for ecological restoration spraying according to claim 1, characterized in that: The usage ratio of Tris-HCl buffer, anhydrous ethanol, dopamine hydrochloride, terminal thiol hyperbranched polyester and pretreated straw fiber in S1 is 20-30 mL: 20-30 mL: 0.16-0.20 g: 0.085-0.1 g: 3-4 g.

3. The straw fiber adsorption material for ecological restoration spraying according to claim 1, characterized in that: The usage ratio of the intermediate product, deionized water and chloroacetic acid in S2 is 3-4 g: 40-60 mL: 0.3-0.6 g.

4. The straw fiber adsorption material for ecological restoration spraying according to claim 1, characterized in that: The molar ratio of triethanolamine to 4-mercaptopyridinedicarboxylic acid is 1:1, and the amount of p-toluenesulfonic acid used is 2-3% of the mass of triethanolamine and 4-mercaptopyridinedicarboxylic acid.

5. The straw fiber adsorption material for ecological restoration spraying according to claim 1, characterized in that: The dosage ratio of corn straw fiber to sodium hypochlorite solution is 1-2 g:10 mL, and the mass fraction of sodium hypochlorite solution is 0.5-1.5%.