Preparation method of modified salix psammophila fiber and application of modified salix psammophila fiber in wind prevention and sand fixation

Abstract

The invention belongs to the technical field of desert control, and particularly relates to a preparation method of modified salix psammophila fibers and application of the modified salix psammophila fibers in wind prevention and sand fixation. The method comprises the following steps: pretreating salix psammophila fibers by adopting a deep eutectic solvent formed by betaine and lactic acid, and carrying out grafting reaction in an acrylic acid solution by taking N, N '-methylene bisacrylamide as a cross-linking agent and taking a potassium persulfate solution as an initiator to realize modification treatment on the salix psammophila fibers; the porosity, the water absorption rate and the tensile strength of the modified salix mongolica fiber are remarkably improved; the weaved blanket for preventing wind and fixing sand is weaved by using the modified salix psammophila fiber and the polylactic acid fiber as raw materials, the obtained weaved blanket has relatively high water absorption and permeation rate, water retention rate and water retention capacity, the germination rate of seeds embedded in the weaved blanket can reach 70% or above, and desert oasis can be realized after the weaved blanket is applied to desert control for a long time.

Description

Technical Field

[0001] The present invention belongs to the field of desert control technology, and specifically relates to a preparation method of modified Salix psammophila fiber and its application in windbreak and sand fixation. Background Art

[0002] Desertification is caused by factors such as drought, lack of rainfall, vegetation destruction, overgrazing, wind erosion, water erosion, and soil salinization. Currently, major sand control projects include physical, chemical, and plant-based projects. Among these, straw grids, the most commonly used, are often made of materials like wheat straw and reeds, which have low water retention and a short lifespan of 8-12 months. Chemically synthesized polyethylene grids, on the other hand, can cause environmental pollution and damage ecological structures.

[0003] Salix psammophila fiber is often used as a raw material for windbreak and sand-fixing blankets due to its well-defined shape, large aspect ratio, and small wall-to-cavity ratio. However, the natural porosity of Salix psammophila fiber is only 12-15%, and its water absorption rate is approximately 200%, which does not meet the water threshold for plant germination in arid regions (>500%). It also has low tensile strength and a short service life. Existing methods for modifying Salix psammophila fiber primarily rely on chemical techniques, such as acid-base etching and organic solvent grafting, which can easily leave residual chemical reagents that inhibit the growth of microorganisms in the sand. Furthermore, existing windbreak and sand-fixing blankets primarily utilize a single-layer structure, resulting in a poor windbreak and sand-fixing system that is unlikely to achieve long-term control effects. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a preparation method for modified Salix psammophila fiber and its application in windbreak and sand fixation. The Salix psammophila fiber is pretreated with a low eutectic solvent formed by a mixture of betaine and lactic acid, and a grafting reaction is carried out in an acrylic acid solution using N,N'-methylenebisacrylamide as a cross-linking agent and a potassium persulfate solution as an initiator to achieve modification of the Salix psammophila fiber. The porosity, water absorption rate and tensile strength of the modified Salix psammophila fiber are significantly improved. A windbreak and sand fixation woven blanket is woven using modified Salix psammophila fiber and polylactic acid fiber as raw materials. The resulting woven blanket has strong water absorption and water permeability, and a high water retention rate. Seeds are embedded in the woven blanket, and the germination rate can reach more than 70%.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for preparing modified Salix psammophila fiber comprises the following steps: S1. Pretreatment: Refining the Salix psammophila fibers to obtain fiber bundles with a diameter of 5-12 cm, cleaning them, and immersing them in a low eutectic solvent formed by a mixture of betaine and lactic acid at 60-85°C for 2-5 hours to form a porous structure in the Salix psammophila fibers. The fibers are then rinsed with deionized water at 60°C and dried to obtain pretreated Salix psammophila fibers. S2. Grafting treatment: Immerse the pretreated Salix psammophila fiber described in S1 in a mixed solution obtained by mixing an acrylic acid solution and an N,N'-methylenebisacrylamide solution, then drop a potassium persulfate solution into it, and heat the mixture in a water bath at 50-70°C under a nitrogen environment for 1-3 hours. After the reaction is completed, rinse it with deionized water at 50°C, and then dry it to obtain modified Salix psammophila fiber.

[0006] Here, the acrylic acid solution refers to an aqueous solution of acrylic acid, and the N,N'-methylenebisacrylamide solution refers to an aqueous solution of N,N'-methylenebisacrylamide.

[0007] The pretreated Salix tamarisk fibers were grafted, with a grafting rate of 20-25% and an absorption rate increased to 700%.

[0008] Preferably, the low eutectic solvent formed by mixing betaine and lactic acid in S1 is formed by mixing betaine and lactic acid in a molar ratio of 1:1~4, and the amount ratio of the fiber bundle to the low eutectic solvent is 1:15~18kg / L; the drying temperature is 70~80℃, and the time is 3~5h.

[0009] Preferably, the mixed solution described in S2 is a mixture of acrylic acid solution and N,N'-methylenebisacrylamide solution in a volume ratio of 5~15:1, the concentration of acrylic acid solution is 5~20 wt%, the concentration of N,N'-methylenebisacrylamide solution is 1~3 wt%, and the dosage ratio of pretreated Salix psammophila fiber to the mixed solution is 1:20 kg / L; the concentration of potassium persulfate solution is 0.4~0.8 wt%, and the amount dropped into the mixed solution is 1~4 mL / L.

[0010] Here, the potassium persulfate solution refers to an aqueous solution of potassium persulfate.

[0011] Preferably, the drying process in step S2 is carried out at a temperature of 70 to 80° C. for 6 to 8 hours.

[0012] The modified Salix psammophila fiber is applied to the preparation of a windbreak and sand-fixing woven blanket. The obtained woven blanket uses polylactic acid fiber as a supporting skeleton and is composited with the modified Salix psammophila fiber to construct a multi-gradient layer structure.

[0013] The preparation method of the windproof and sand-fixing woven blanket is as follows: A1. Surface preparation: The surface layer is woven using 0.5-10 mm polylactic acid fibers using an orthogonal weaving method. The resulting surface layer has a mesh size of ≤3×3 mm, a thickness of 0.3-0.5 mm, and a tensile strength of ≥2000 N / m. The orthogonal weaving method refers to a method of completing the weaving by controlling the introduction action and order of the polylactic acid fibers in the warp and weft directions so that the fibers in the warp and weft directions are interwoven perpendicularly to each other.

[0014] In the process of desert control, the size of the surface mesh is adjusted according to the intensity of wind erosion in different desert areas. For example, in areas with strong wind erosion, the mesh size can be adjusted to ≤1×1mm; in areas with weak wind erosion, the mesh size can be adjusted to ≤3×3mm. A2. Preparation of the initial water-absorbing layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and then needle-punched at a needle-punching density of 150 to 300 needles / cm 2 , the initial water-absorbing layer is obtained, with a porosity of 45-55%, a thickness of 1.5-2.0 cm, and a water permeability of 30-80 mm / h; The obtained initial water-absorbing layer can achieve a water absorption rate of ≥500% within 5 seconds; A3. Preparation of secondary layer: The modified Salix psammophila fiber was uniformly mixed with 0.5-10 mm polylactic acid fiber and woven using a bias weaving method to obtain a secondary layer having a porosity of 35-45% and a thickness of 2.0-2.5 mm; Among them, the oblique weaving method means that during the weaving process, the fiber bundles interwoven along two directions are not perpendicular to each other, and the small angle formed is less than 90° or the large angle is greater than 180°; in the oblique weaving method described in this patent, the small angle formed between the fiber bundles interwoven along two directions is in the range of 30~60°.

[0015] The secondary layer obtained in A3 can balance the water permeability and water retention properties of the resulting woven blanket; A4. Preparation of a water storage layer: The modified Salix psammophila fibers are laid on the surface layer described in A1 and then needle-punched at a density of 200-400 needles / cm² to obtain an aquifer having a porosity of 25-35%, a thickness of 3.0-3.5 mm, and a water retention rate of ≥70%; A5. Preparation of seed layer: The modified Salix psammophila fibers are laid on the surface layer described in A1 and then needle-punched at a needle-punching density of 150-300 needles / cm 2 , a seed layer is obtained with a porosity of 40-45% and a thickness of 1.0-1.2 mm; drought-tolerant plant seeds are selected, a water-retaining agent is added at a mass ratio of 5-10%, and the mixture is evenly mixed, and the seeds are embedded in the seed layer at an embedding density of 30-300 seeds / m 2 ;Seed germination rate ≥70%; A6. Base layer preparation: Use 0.5-10 mm polylactic acid fibers and weave the base layer using an orthogonal weaving method. The resulting base layer has a mesh size of 2×2 mm and a thickness of 0.8-1.0 mm. The wind erosion resistance threshold is ≥15-25 m / s and the water permeability is ≥50-100 mm / h. A7. Stack the surface layer, initial water absorption layer, secondary layer, water storage layer, seed layer, and bottom layer described in A1 to A6 in order from top to bottom, and then mechanically press them together to form an integrated woven blanket. A8. Calendering the surface of the woven blanket obtained in A7 with a hot roller to improve its surface smoothness, then evenly spraying a mixture of chitosan and glycerol at a concentration of 2 wt %. The resulting woven blanket was placed in a hot air circulation oven and dried at 50° C. for 2 to 4 h to obtain a windbreak and sand fixation woven blanket. The 2 wt % chitosan and glycerol mixture means that the mass concentration of chitosan and glycerol in the mixed aqueous solution of chitosan and glycerol is 2%.

[0016] Preferably, the water-retaining agent described in A5 is a starch-based water-retaining agent, model: KM3005, manufacturer: Zhengzhou Fengyue Chemical Products Co., Ltd.

[0017] Preferably, the bottom layer described in A6 has integrated barb anchoring thorns or corrugated texture, wherein the barb anchoring thorns are 5~12mm in length and 20~30 pieces / m² in density; the peak height of the corrugated texture is 1~3mm and the peak spacing is 5~10mm.

[0018] Wherein, the barb anchoring thorn shape structure is like a fish hook structure, which is curved and barbed, such as Figure 2 As shown, the grip of the bottom layer can be improved to prevent the carpet from moving.

[0019] The barb anchoring thorns or the corrugated texture of the bottom layer of the obtained woven carpet can improve the gripping function of the woven carpet.

[0020] Preferably, the pressure of the mechanical pressing in S7 is 5-8 MPa.

[0021] Preferably, the chitosan and glycerol mixture is prepared by mixing chitosan and glycerol in a mass ratio of 1:1 to 3.

[0022] Compared with the prior art, the present invention has the following advantages: (1) The present invention uses a low eutectic solvent formed by betaine and lactic acid to pretreat the Salix psammophila fiber, which can form a porous structure of the Salix psammophila fiber; in an acrylic acid solution, N,N'-methylenebisacrylamide is used as a crosslinking agent and a potassium persulfate solution is used as an initiator to graft the Salix psammophila fiber, and the grafting rate can reach 25%, thereby achieving green modification of the Salix psammophila fiber without chemical reagent residue, avoiding chemical pollution to the desert land, and improving the porosity, water absorption rate and tensile strength of the Salix psammophila fiber; (2) Compared with the existing technology, after modification using the method described in the present invention, the porosity of the Salix psammophila fiber can be increased to 22%, the water absorption rate can reach up to 1200%, and the tensile strength can reach 3500N / m, which significantly improves and enhances the various performance parameters of the Salix psammophila fiber. When applied to desert control, it can extend the service life and improve the windbreak and sand fixation control effect; (3) In the technical solution of the present invention, modified Salix psammophila fibers are applied to a windbreak and sand fixation woven blanket, and the porosity, water retention rate and tensile strength of the resulting woven blanket are significantly improved; by designing the structure of the woven blanket, it is composed of a surface layer, an initial water absorption layer, a secondary layer, a water storage layer, a seed layer and a bottom layer in sequence, and the layers are pressed together by a machine to obtain an integrated woven blanket; the surface layer made of polylactic acid fibers can provide a tensile skeleton for the woven blanket, and the barbed anchoring thorns or corrugated texture of the bottom layer can improve its grip function. The modified Salix psammophila fibers and polylactic acid fibers in the middle layers work together to improve the moisture storage capacity of the woven blanket; (4) The woven blanket of the present invention is applied to desert control, which can quickly and efficiently lock sand and gravel, store moisture, and the plant seeds embedded in the seed layer have a high germination rate, and after germination, the desert can be transformed into an oasis. In addition, the woven blanket has high tensile strength and a long service life, and can be used for a long time to improve desert land, restore ecology, and achieve the purpose of windbreak and sand fixation.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram of a woven blanket; Figure 2 Schematic diagram of the layered structure of a woven blanket. DETAILED DESCRIPTION

[0025] Example 1 This embodiment discloses a method for preparing modified Salix psammophila fiber and the use of the modified Salix psammophila fiber in the preparation of a windbreak and sand-fixing woven blanket. The preparation of the modified Salix psammophila fiber specifically includes the following steps: S1. Pretreatment: Refining Salix psammophila fibers to obtain fiber bundles with a diameter ranging from 5 to 12 cm, cleaning them, and immersing them in a deep eutectic solvent formed by mixing betaine and lactic acid in a molar ratio of 1:2 at a ratio of 1:15 kg / L. The fibers were then soaked at 80°C for 3 h, rinsed with deionized water at 60°C, and dried at 70°C for 3 h to obtain pretreated Salix psammophila fibers. S2. Grafting treatment: The pretreated Salix psammophila fiber described in S1 was immersed in a mixed solution of 8 wt % acrylic acid solution and 1 wt % N,N'-methylenebisacrylamide solution in a volume ratio of 8:1 at a ratio of 1:20 kg / L, and then 0.5 wt % potassium persulfate solution was dropped into it at a volume of 2 mL / L. Then, the mixture was heated in a water bath at 60°C under a nitrogen environment for 2 h. After the reaction, it was rinsed with deionized water at 50°C and then dried at 70°C for 8 h to obtain modified Salix psammophila fiber. After pretreatment, the porosity of the Salix psammophila fiber increased to 18% and the water absorption rate increased to 550%. After grafting, the grafting rate reached 25%. The tensile strength of the modified Salix psammophila fiber was greater than 1800N / m. The modified Salix psammophila fibers obtained through modification are applied to the preparation of windbreak and sand-fixing woven blankets. The method for preparing the woven blanket is as follows: A1. Surface layer preparation: The surface layer is woven using polylactic acid fibers with a diameter ranging from 0.5 to 10 mm using an orthogonal weaving method. The mesh size of the resulting surface layer is ≤ 3 × 3 mm, the thickness is within the range of 0.3 to 0.5 mm, and the tensile strength is ≥ 2000 N / m. A2. Preparation of the initial water-absorbing layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and then needle-punched at a needle-punching density of 150 needles / cm 2 , the initial water absorption layer was obtained with a porosity of 45%, a thickness in the range of 1.5-2.0 cm, a water permeability in the range of 30-50 mm / h, and a water absorption rate greater than 500%; A3. Preparation of secondary layer: The modified Salix psammophila fiber was uniformly mixed with 0.5-10 mm polylactic acid fiber and woven using a bias weaving method with a bias angle of 30° to obtain a secondary layer with a porosity of 35% and a thickness in the range of 2.0-2.5 mm. A4. Preparation of a water storage layer: The modified Salix psammophila fibers are laid on the surface layer described in A1 and then needle-punched at a density of 200 needles / cm² to obtain an aquifer having a porosity of 25%, a thickness of 3.0-3.5 mm, and a water retention rate of ≥70%; A5. Preparation of seed layer: The modified Salix psammophila fiber was spread on the surface layer described in A1 and then needled at a density of 200 needles / cm² to obtain a seed layer with a porosity of 40% and a thickness of 1.0-1.2 mm. Drought-tolerant plant seeds were selected, starch-based water-retaining agent was added at a mass ratio of 5%, and after stirring evenly, the seeds were embedded in the seed layer at an embedding density of 30 seeds / m². 2 ; A6. Base layer preparation: 0.5-10 mm polylactic acid fibers are orthogonally woven to form a base layer with 5 mm long integrated barbed anchors at a density of 20 per square meter. The mesh size is 2 x 2 mm, the thickness is between 0.8 and 1.0 mm, the wind erosion resistance threshold is ≥ 15 m / s, and the water permeability is ≥ 50 mm / h. A7, the layers described in A1~A6, Figure 2 As shown, the layers are stacked in the order of surface layer, initial water absorption layer, secondary layer, water storage layer, seed layer and bottom layer. The stacking effect is as follows: Figure 1 As shown, a mechanical pressing process is then performed at 5 MPa to form an integrated woven blanket. A8. After calendering the surface of the woven blanket described in A7 with a hot roller, evenly spray a 2 wt% chitosan and glycerol mixture prepared by mixing chitosan and glycerol in a mass ratio of 1:1. Then, place the obtained woven blanket in a hot air circulation oven and dry it at 50°C for 2 hours to obtain a windproof and sand-fixing woven blanket.

[0026] The obtained windbreak and sand-fixing woven blanket has a porosity of 30% and a water retention rate of 78%. When used in desert control, the water retention capacity can reach 3.1L / m 2 , the water permeability is 50mm / h, the tensile strength is 1800N / m, the degradation cycle is 24 months, the wind erosion resistance threshold is 20m / s, and the germination rate of seeds embedded in the seed layer can reach 68%.

[0027] Example 2 This embodiment discloses a preparation method of modified Salix psammophila fiber and the use of the modified Salix psammophila fiber in the preparation of a windbreak and sand-fixing woven blanket. The preparation method of the modified Salix psammophila fiber specifically comprises the following steps: S1. Pretreatment: Refining Salix psammophila fibers to obtain fiber bundles with a diameter ranging from 5 to 12 cm, cleaning them, and immersing them in a deep eutectic solvent formed by mixing betaine and lactic acid in a molar ratio of 1:4 at a ratio of 1:15 kg / L. After soaking at 85°C for 5 h, the fibers were rinsed with deionized water at 60°C and dried at 80°C for 5 h to obtain pretreated Salix psammophila fibers. S2. Grafting treatment: The pretreated Salix psammophila fiber described in S1 was immersed in a mixed solution of 15 wt% acrylic acid solution and 1 wt% N,N'-methylenebisacrylamide solution in a volume ratio of 12:1 at a ratio of 1:20 kg / L, and then 0.7 wt% potassium persulfate solution was dropped into it at a volume of 3 mL / L. The mixture was heated in a water bath at 70°C under a nitrogen environment for 3 h. After the reaction, it was rinsed with deionized water at 50°C and dried at 80°C for 8 h to obtain modified Salix psammophila fiber. After pretreatment, the porosity of the Salix psammophila fiber increased to 22% and the water absorption rate increased to 1200%. After grafting, the grafting rate reached 25%. The tensile strength of the modified Salix psammophila fiber was greater than 3500N / m. The modified Salix psammophila fibers obtained through modification are applied to the preparation of windbreak and sand-fixing woven blankets. The method for preparing the woven blanket is as follows: A1. Surface preparation: The surface layer is woven using 0.5-10 mm polylactic acid fibers using an orthogonal weaving method. The mesh size of the resulting surface layer is ≤3×3 mm, the thickness is within the range of 0.3-0.5 mm, and the tensile strength is ≥2000 N / m. A2. Preparation of the initial water-absorbing layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and then needle-punched at a needle-punching density of 300 needles / cm 2 , the initial water absorption layer was obtained, with a porosity of 55%, a thickness in the range of 1.5-2.0 cm, a water permeability in the range of 50-80 mm / h, and a water absorption rate greater than 500%; A3. Preparation of secondary layer: The modified Salix psammophila fiber was uniformly mixed with 0.5-10 mm polylactic acid fiber and woven using a bias weaving method with a bias angle of 60° to obtain a secondary layer with a porosity of 45% and a thickness in the range of 2.0-2.5 mm. A4. Preparation of a water storage layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and needle-punched at a density of 400 needles / cm² to obtain an aquifer having a porosity of 35%, a thickness of 3.0-3.5 mm, and a water retention rate of ≥70%. A5. Preparation of seed layer: The modified Salix psammophila fibers were spread on the surface layer described in A1 and needle-punched at a density of 400 needles / cm² to obtain a seed layer with a porosity of 45% and a thickness of 1.0-1.2 mm. Drought-tolerant plant seeds were selected, starch-based water-retaining agent was added at a mass ratio of 10%, and after stirring evenly, the seeds were embedded in the seed layer at an embedding density of 300 seeds / m². 2 ; A6. Base layer preparation: 0.5-10 mm polylactic acid fibers are orthogonally woven to form a base layer with 12 mm long integrated barbed anchors at a density of 30 per square meter. The mesh size is 2 x 2 mm, and the thickness is within the range of 0.8-1.0 mm. The wind erosion resistance threshold is ≥ 25 m / s, and the water permeability is ≥ 100 mm / h. A7, the layers described in A1~A6, Figure 2 As shown, the layers are stacked in the order of surface layer, initial water absorption layer, secondary layer, water storage layer, seed layer and bottom layer. The stacking effect is as follows: Figure 1 As shown, the blanket is then pressed mechanically at 8 MPa to form an integrated woven blanket. A8. After calendering the surface of the woven blanket described in A7 with a hot roller, evenly spray a 2 wt% chitosan and glycerol mixture formed by mixing chitosan and glycerol in a mass ratio of 1:3. Then, place the obtained woven blanket in a hot air circulation oven and dry it at 50°C for 4 hours to obtain a windproof and sand-fixing woven blanket.

[0028] The obtained windbreak and sand-fixing woven blanket has a porosity of 25% and a water retention rate of 85%. When used in desert control, the water retention capacity can reach 7.0L / m 2 , the water permeability is 20mm / h, the tensile strength is 3500N / m, the degradation cycle is 36 months, the wind erosion resistance threshold is 25m / s, and the germination rate of seeds embedded in the seed layer can reach 72%.

[0029] Example 3 This embodiment discloses a preparation method of modified Salix psammophila fiber and the use of the modified Salix psammophila fiber in the preparation of a windbreak and sand-fixing woven blanket. The preparation method of the modified Salix psammophila fiber specifically comprises the following steps: S1. Pretreatment: Refining Salix psammophila fibers to obtain fiber bundles with a diameter ranging from 5 to 12 cm, cleaning them, and immersing them in a deep eutectic solvent formed by mixing betaine and lactic acid in a molar ratio of 1:15 kg / L at 60°C for 2 h, rinsing them with deionized water at 60°C, and drying them at 70°C for 4 h to obtain pretreated Salix psammophila fibers. S2. Grafting treatment: The pretreated Salix psammophila fibers described in S1 were immersed in a mixed solution of 5 wt% acrylic acid solution and 3 wt% N,N'-methylenebisacrylamide solution in a volume ratio of 5:1 at a ratio of 1:20 kg / L, and then 0.4 wt% potassium persulfate solution was dropped into it at a volume of 1 mL / L. The mixture was heated in a water bath at 50°C under a nitrogen atmosphere for 1 h. After the reaction, the fibers were rinsed with deionized water at 50°C and then dried at 70°C for 6 h to obtain modified Salix psammophila fibers. After pretreatment, the porosity of the Salix psammophila fiber increased to 20% and the water absorption rate increased to 550%. After grafting, the grafting rate reached 22%. The tensile strength of the modified Salix psammophila fiber was greater than 2500N / m. The modified Salix psammophila fibers obtained through modification are applied to the preparation of windbreak and sand-fixing woven blankets. The method for preparing the woven blanket is as follows: A1. Surface preparation: The surface layer is woven using 0.5-10 mm polylactic acid fibers using an orthogonal weaving method. The mesh size of the resulting surface layer is ≤3×3 mm, the thickness is within the range of 0.3-0.5 mm, and the tensile strength is ≥2000 N / m. A2. Preparation of the initial water-absorbing layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and then needle-punched at a needle-punching density of 200 needles / cm 2 , the initial water absorption layer is obtained, with a porosity of 40%, a thickness in the range of 1.5-2.0 cm, a water permeability in the range of 40-60 mm / h, and a water absorption rate greater than 500%; A3. Preparation of secondary layer: The modified Salix psammophila fiber was uniformly mixed with 0.5-10 mm polylactic acid fiber and woven using a bias weaving method with a bias angle of 40° to obtain a secondary layer with a porosity of 40% and a thickness in the range of 2.0-2.5 mm. A4. Preparation of a water storage layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and needled at a needle density of 300 needles / cm² to obtain an aquifer having a porosity of 30%, a thickness of 3.0-3.5 mm, and a water retention rate of ≥70%. A5. Preparation of seed layer: The modified Salix psammophila fiber is spread on the surface layer described in A1 and then needle-punched at a density of 300 needles / cm² to obtain a seed layer with a porosity of 40% and a thickness of 1.0-1.2 mm. Drought-tolerant plant seeds are selected, starch-based water-retaining agent is added at a mass ratio of 8%, and after stirring evenly, the seeds are embedded in the seed layer at an embedding density of 200 seeds / m². 2 ; A6. Base layer preparation: 0.5-10 mm polylactic acid fibers are orthogonally woven to form a base layer with a corrugated texture with a peak height of 1-3 mm and a peak spacing of 5-10 mm. The base layer has a mesh size of 2 × 2 mm and a thickness of 0.8-1.0 mm. The wind erosion resistance threshold is ≥ 25 m / s and the water permeability is ≥ 80 mm / h. A7, the layers described in A1~A6, Figure 2 As shown, the layers are stacked in the order of surface layer, initial water absorption layer, secondary layer, water storage layer, seed layer and bottom layer. The stacking effect is as follows: Figure 1 As shown, the machine is then pressed at 6 MPa to form an integrated woven blanket. A8. After calendering the surface of the woven blanket described in A7 with a hot roller, evenly spray a 2 wt% chitosan and glycerol mixture formed by mixing chitosan and glycerol in a mass ratio of 1:3. Place the resulting woven blanket in a hot air circulation oven and dry it at 50°C for 4 hours to obtain a windproof and sand-fixing woven blanket.

[0030] The obtained windbreak and sand-fixing woven blanket is a fast-degrading woven blanket with a porosity of 45% and a water retention rate of 70%. When used in desert control, the water retention can reach 3.8L / m 2 , water permeability is 80mm / h, tensile strength is greater than 800N / m, degradation cycle is 12 months, wind erosion resistance threshold is 15m / s, and the germination rate of seeds embedded in the seed layer can reach 65%.

[0031] Example 4 This embodiment discloses a preparation method of modified Salix psammophila fiber and the use of the modified Salix psammophila fiber in a windbreak and sand-fixing woven blanket. The preparation method of the modified Salix psammophila fiber specifically comprises the following steps: S1. Pretreatment: Refining Salix psammophila fibers to obtain fiber bundles with a diameter ranging from 5 to 12 cm, cleaning them, and immersing them in a deep eutectic solvent formed by mixing betaine and lactic acid in a molar ratio of 1:3 at a ratio of 1:18 kg / L. After soaking at 70°C for 4 h, the fibers were rinsed with deionized water at 60°C, and then dried at 75°C for 5 h to obtain pretreated Salix psammophila fibers. S2. Grafting treatment: The pretreated Salix psammophila fibers described in S1 were immersed in a mixed solution of 20 wt% acrylic acid solution and 2 wt% N,N'-methylenebisacrylamide solution in a volume ratio of 15:1 at a ratio of 1:20 kg / L, and then 0.8 wt% potassium persulfate solution was dropped into it at a volume of 2 mL / L. The mixture was heated in a water bath at 65°C under a nitrogen environment for 3 h. After the reaction, it was rinsed with deionized water at 50°C and then dried at 75°C for 7 h to obtain modified Salix psammophila fibers. After pretreatment, the porosity of the Salix psammophila fiber increased to 22% and the water absorption rate increased to 750%. After grafting, the grafting rate reached 22%. The tensile strength of the modified Salix psammophila fiber was greater than 2500N / m. The modified Salix psammophila fibers obtained through modification are applied to the preparation of windbreak and sand-fixing woven blankets. The method for preparing the woven blanket is as follows: A1. Surface preparation: The surface layer is woven using 0.5-10 mm polylactic acid fibers using an orthogonal weaving method. The mesh size of the resulting surface layer is ≤3×3 mm, the thickness is within the range of 0.3-0.5 mm, and the tensile strength is ≥2000 N / m. A2. Preparation of the initial water-absorbing layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and then needle-punched at a needle-punching density of 300 needles / cm 2 , the initial water absorption layer is obtained, with a porosity of 50%, a thickness in the range of 1.5-2.0 cm, a water permeability in the range of 70-80 mm / h, and a water absorption rate greater than 500%; A3. Preparation of secondary layer: The modified Salix psammophila fiber was uniformly mixed with 0.5-10 mm polylactic acid fiber and woven using a bias weaving method with a bias angle of 50° to obtain a secondary layer with a porosity of 45% and a thickness in the range of 2.0-2.5 mm. A4. Preparation of a water storage layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and needled at a needle density of 350 needles / cm² to obtain an aquifer having a porosity of 32%, a thickness of 3.0-3.5 mm, and a water retention rate of ≥70%. A5. Preparation of seed layer: The modified Salix psammophila fiber is spread on the surface layer described in A1 and then needle-punched at a density of 350 needles / cm² to obtain a seed layer with a porosity of 40% and a thickness of 1.0-1.2 mm. Drought-tolerant plant seeds are selected, starch-based water-retaining agent is added at a mass ratio of 7%, and after stirring evenly, the seeds are embedded in the seed layer at an embedding density of 300 seeds / m². 2 ; A6. Base layer preparation: 0.5-10 mm polylactic acid fibers are orthogonally woven to produce a corrugated texture with a peak height of 1-3 mm and a peak spacing of 10 mm. The mesh size is 2 × 2 mm, the thickness is 0.8-1.0 mm, the wind erosion resistance threshold is ≥ 25 m / s, and the water permeability is ≥ 70 mm / h. A7, the layers described in A1~A6, Figure 2 As shown, the layers are stacked in the order of surface layer, initial water absorption layer, secondary layer, water storage layer, seed layer and bottom layer. The stacking effect is as follows: Figure 1 As shown, a mechanical pressing process is then performed at 6 MPa to form an integrated woven blanket. A8. After calendering the surface of the woven blanket described in A7 with a hot roller, evenly spray a 2 wt% chitosan and glycerol mixture formed by mixing chitosan and glycerol in a mass ratio of 1:2. Place the resulting woven blanket in a hot air circulation oven and dry it at 50°C for 4 hours to obtain a windproof and sand-fixing woven blanket.

[0032] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing modified Salix psammophila fiber, characterized in that: The steps include: S1. Pretreatment: Refining Salix psammophila fibers to obtain fiber bundles with a diameter of 5 to 12 cm, cleaning them, and immersing them in a deep eutectic solvent formed by a mixture of betaine and lactic acid at 60 to 85°C for 2 to 5 hours, then rinsing them with deionized water at 60°C, and drying them to obtain pretreated Salix psammophila fibers; S2. Grafting treatment: acrylic acid solution and N,N'-methylenebisacrylamide solution are mixed in a volume ratio of 5~15:1 to form a mixed solution. The pretreated Salix psammophila fiber obtained in S1 is immersed in the mixed solution, and then potassium persulfate solution is dropped into it. In a nitrogen environment, the mixture is heated in a water bath at 50~70℃ for 1~3h, and then rinsed with deionized water at 50℃ and dried to obtain modified Salix psammophila fiber.

2. The method for preparing modified Salix psammophila fiber according to claim 1, characterized in that: The deep eutectic solvent described in S1 is a mixture of betaine and lactic acid in a molar ratio of 1:1-4; the dosage ratio of the fiber bundle to the deep eutectic solvent is 1:15-18 kg / L; the drying temperature is 70-80° C. and the drying time is 3-5 hours.

3. The method for preparing modified Salix psammophila fiber according to claim 1, characterized in that: The concentration of the acrylic acid solution described in S2 is 5~20 wt%, and the concentration of the N,N'-methylenebisacrylamide solution is 1~3 wt%; the dosage ratio of the pretreated Salix psammophila fiber to the mixed solution is 1:20 kg / L; the concentration of the potassium persulfate solution is 0.4~0.8 wt%, and the amount added to the mixed solution is 1~4 mL / L.

4. The method for preparing modified Salix psammophila fiber according to claim 1, characterized in that: The drying process in S2 is carried out at a temperature of 70 to 80° C. for 6 to 8 hours.

5. Application of modified Salix psammophila fiber in windbreak and sand fixation, characterized in that: The modified Salix psammophila fiber prepared by the method according to any one of claims 1 to 4 is applied to the preparation of a windproof and sand-fixing woven blanket.

6. The use according to claim 5, characterized in that The preparation method of the windproof and sand-fixing woven blanket is as follows: A1. Surface layer preparation: The surface layer is woven using polylactic acid fibers with a diameter of 0.5-10 mm using an orthogonal weaving method. The mesh size of the resulting surface layer is ≤3×3 mm, the thickness is 0.3-0.5 mm, and the tensile strength is ≥2000 N / m. A2. Preparation of the initial water-absorbing layer: The modified Salix psammophila fibers were placed on the surface layer described in A1 and needle-punched at a needle-punching density of 150 to 300 needles / cm 2 , to obtain an initial water-absorbing layer with a thickness of 1.5~2.0 cm; A3. Preparation of secondary layer: The modified Salix psammophila fiber and polylactic acid fiber with a diameter of 0.5-10 mm were uniformly mixed and woven using a bias weaving method to obtain a secondary layer with a thickness of 2.0-2.5 mm. A4. Preparation of a water storage layer: The modified Salix psammophila fibers were laid on the surface layer described in A1 and needled at a density of 200 to 400 needles / cm² to obtain an aquifer having a thickness of 3.0 to 3.5 mm. A5. Preparation of seed layer: The modified Salix psammophila fiber is laid on the surface layer described in A1 and then needle-punched at a needle density of 200-400 needles / cm² to obtain a seed layer with a thickness of 1.0-1.2 mm; Select drought-resistant plant seeds, add water-retaining agent and stir evenly, then embed them into the seed layer with an embedding density of 30-300 seeds / m 2 ; A6. Preparation of the bottom layer: Use polylactic acid fibers with a diameter of 0.5-10 mm and weave the bottom layer by orthogonal weaving. The mesh size of the bottom layer is 2×2 mm, the thickness is 0.8-1.0 mm, and the wind erosion resistance threshold is ≥15-25 m / s. A7. Stack the surface layer, initial water absorption layer, secondary layer, water storage layer, seed layer, and bottom layer described in A1 to A6 in order from top to bottom, and then mechanically press them together to form an integrated woven blanket. A8. After calendering the surface of the woven blanket described in A7 with a hot roller, a mixture of chitosan and glycerol with a concentration of 2 wt% was evenly sprayed on it, and then placed in a hot air circulation box and dried at 50°C for 2-4 hours to obtain a windproof and sand-fixing woven blanket.

7. The use according to claim 6, characterized in that The water-retaining agent described in A5 is a starch-based water-retaining agent, and the dosage is 5-10%.

8. The use according to claim 6, characterized in that The bottom layer described in A6 has barbed anchor thorns or a corrugated texture, wherein the barbed anchor thorns are 5-12 mm in length and 20-30 pieces / m² in density; the peak height of the corrugated texture is 1-3 mm and the peak spacing is 5-10 mm.

9. The use according to claim 6, characterized in that The pressure of the mechanical pressing treatment described in A7 is 5~8MPa.

10. The use according to claim 6, characterized in that The mixed solution of chitosan and glycerol described in A8 is prepared by mixing chitosan and glycerol in a mass ratio of 1:1 to 3.

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