Degradable bagasse mulching film loaded with ground phosphate rock as well as preparation and application of degradable bagasse mulching film

Abstract

The invention provides a degradable bagasse mulching film loaded with ground phosphate rock as well as preparation and application of the degradable bagasse mulching film. Bagasse is used as a main raw material, and the multifunctional mulching film with soil moisture conservation and slow-release fertilizer efficiency is prepared by loading ground phosphate rock and optimizing a process. Nutrients can be released in the degradation process, the content of organic matters and available phosphorus in soil is remarkably increased, and fertilizer loss and labor cost are reduced. According to the technology, high-value utilization of agricultural waste is achieved, dependence on petrochemical resources is reduced, degradation products are non-toxic, and the soil structure can be improved. Compared with the prior art, the method is low in material cost, simple in process, controllable in degradation rate and suitable for large-scale production and popularization, and has good ecological benefits, economic benefits and social benefits. The mulching film provides an innovative solution for green agriculture and shows a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the field of degradable mulch films, and in particular relates to a degradable bagasse mulch film loaded with phosphate rock powder, and a preparation method and application thereof. Background Art

[0002] Traditional plastic mulch is widely used in agricultural production, significantly increasing crop yields by reducing water evaporation, improving soil moisture retention, raising soil temperatures, and suppressing weed growth. However, its primary raw material, petroleum-based plastic, is difficult to degrade naturally. Long-term use leaves residues in the soil, causing "white pollution," damaging soil ecology, and reducing crop quality. Furthermore, because traditional mulch is thin and fragile, recycling costs are high, making the pollution problem difficult to fundamentally address.

[0003] Bagasse, a byproduct of the sugar industry, is rich in natural polymers such as cellulose, hemicellulose, and lignin. It exhibits excellent biodegradability, abundant reserves, and low cost. Using bagasse to create biodegradable mulch not only naturally degrades into carbon dioxide, water, and organic matter, preventing soil pollution, but also allows for high-value waste utilization, reducing reliance on petrochemical resources and offering a new direction for the development of environmentally friendly agricultural materials. Furthermore, loading fertilizer into biodegradable bagasse mulch offers a multifunctional solution: on the one hand, the mulch slowly releases nutrients as it degrades, meeting crop needs throughout the growing cycle; on the other hand, the fertilizer-loaded mulch reduces fertilizer loss, improves utilization efficiency, and reduces fertilization frequency and labor costs. Combined with the mulch's thermal insulation and moisture-retaining properties, this composite material provides an ideal environment for crop growth, helping to increase agricultural yields and resource efficiency.

[0004] The development of a biodegradable bagasse mulch film capable of loading fertilizer offers ecological, economic, and social benefits. Ecologically, this film reduces plastic pollution and protects the soil microecological environment. Economically, it reduces production costs and improves resource efficiency by recycling agricultural waste. Socially, it promotes the green transformation of agriculture and contributes to the achievement of sustainable development goals. However, technological advancement still requires addressing challenges such as optimizing mechanical properties, regulating degradation rates, and precisely releasing fertilizers. By integrating environmental protection with agriculture, this technology offers innovative solutions for green agriculture, demonstrating broad application prospects and significant value. Summary of the Invention

[0005] In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a method for preparing a degradable bagasse mulch film loaded with phosphate rock powder.

[0006] Another object of the present invention is to provide a degradable bagasse mulch film loaded with phosphate rock powder prepared by the above method.

[0007] Another object of the present invention is to provide an application of the above-mentioned degradable bagasse mulch film loaded with phosphate rock powder.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing a degradable bagasse mulch film loaded with phosphate rock powder comprises the following steps:

[0010] (1) mixing expanded bagasse, phosphate rock and water, heating and stirring to obtain an expanded bagasse solution adsorbing phosphate rock;

[0011] (2) After adding coumarin and / or vanillin to a polyvinyl alcohol solution and heating for reaction, adding a humic acid solution and reacting, then adding a crosslinker solution and heating for reaction, then adding sodium alginate and the expanded bagasse solution adsorbed with phosphate rock powder in step (1) and mixing them uniformly, finally adding a calcium nitrate solution and mixing them uniformly, drying to form a film, dialyzing, and drying to obtain a degradable bagasse mulch film loaded with phosphate rock powder.

[0012] Preferably, the puffed bagasse in step (1) has a neutral detergent fiber content of 62.37-82.37%, an acid detergent fiber content of 47.28-67.28%, an acid detergent lignin content of 5.3-25.3%, and a crude protein content of 2.23-4.23%.

[0013] Preferably, the puffed bagasse in step (1) is obtained by puffing bagasse at 210° C. for 3 to 20 minutes.

[0014] Preferably, the mass ratio of the expanded bagasse, phosphate rock and water in step (1) is 1-10:1-10:1-200; more preferably 2-5:4-10:50.

[0015] Preferably, the heating and stirring temperature in step (1) is 40-60° C., and the stirring time is 0.5-2 h.

[0016] Preferably, the mass ratio of coumarin and / or vanillin to polyvinyl alcohol, humic acid, cross-linking agent, sodium alginate and calcium nitrate in step (2) is 1.5-10:2-25:0.25-1:0.1-1:1-1.5:0.5-0.75; more preferably, it is 2.5-5:5:0.25-1:0.2:1-1.5:0.5-0.75.

[0017] Preferably, the mass ratio of the sodium alginate and the expanded bagasse solution adsorbing phosphate rock powder in step (2) is 1.5-10:40-300; more preferably 1-1.5:56-62.

[0018] Preferably, in the polyvinyl alcohol solution of step (2), the mass ratio of polyvinyl alcohol to solvent volume is 1-10 g:1-200 mL, more preferably 5 g:100 mL; and the solvent is dimethyl sulfoxide.

[0019] Preferably, the polyvinyl alcohol solution in step (2) is obtained by adding polyvinyl alcohol to a solvent and heating and stirring at 70-95° C. for 5-24 hours.

[0020] Preferably, the coumarin and / or vanillin in step (2) is added to a polyvinyl alcohol solution and heated at 70-95° C. for reaction for 0.5-2 h.

[0021] Preferably, in the humic acid solution of step (2), the mass ratio of humic acid to solvent is 1-10:1-200, more preferably 2.5-10:100; and the solvent is dimethyl sulfoxide.

[0022] Preferably, after adding the humic acid solution in step (2), the mixture is stirred for 0.5 to 2 hours and then ultrasonicated for 0.5 to 1 hour.

[0023] Preferably, the total concentration of the cross-linking agent in the cross-linking agent solution in step (2) is 4 to 12 mmol / L; and the solvent is water.

[0024] Preferably, the crosslinking agent in the crosslinking agent solution of step (2) is 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) in a mass ratio of 1:1.

[0025] Preferably, after adding the crosslinking agent solution in step (2), the reaction is heated at 40-60° C. for 5-12 hours.

[0026] Preferably, the sodium alginate and the expanded bagasse solution adsorbed with phosphate rock powder in step (1) are added to the solution in step (2) and then heated and stirred at 70-95° C. for 0.5-3 h.

[0027] Preferably, the mass ratio of calcium nitrate to water in the calcium nitrate solution in step (2) is 0.5-5:10-50, more preferably 0.75:15.

[0028] Preferably, the drying film forming temperature in step (2) is 40-65° C. and the drying time is 24-72 hours.

[0029] Preferably, the dialysis time in step (2) is 24 to 48 hours.

[0030] Preferably, the drying after dialysis in step (2) refers to drying at room temperature for 24 to 48 hours and then drying at 40 to 60° C. for 2 to 7 hours.

[0031] A degradable bagasse mulch film loaded with phosphate rock powder is prepared by the above method.

[0032] Application of the above-mentioned degradable bagasse mulch film loaded with phosphate rock powder.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] (1) The present invention adds the function of loading fertilizer on the basis of traditional ground film, so that it has the dual functions of protection and nutrient supply.

[0035] (2) The mulch film prepared by the present invention has the characteristics of slow-release fertilizer, which can continuously increase soil fertility and improve crop growth effects.

[0036] (3) The present invention uses degradable materials to prepare ground films, which achieves controllability of the degradation process and reduces the risk of environmental pollution.

[0037] (4) The present invention utilizes humic acid and coumarin to significantly improve the mechanical properties of the mulch film and enhance the effective utilization of phosphate rock and expanded bagasse in the soil, thereby increasing the content of organic matter and available phosphorus. Simultaneously, the synergistic effect of expanded bagasse and phosphate rock effectively increases the available phosphorus content in the soil.

[0038] (5) The materials used in the present invention are inexpensive, the preparation process is simple, and it has the potential for large-scale production and wide application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The surface (left) and cross-section (right) SEM images of the ground film of Example 2 show that the thickness of the ground film is measured to be 11.78 μm.

[0040] Figure 2 This is a physical picture of the degradation process of the soil surface covered with mulch film in Example 3 within 40 days. DETAILED DESCRIPTION

[0041] The present invention will be described in further detail below with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.

[0042] In the examples of the present invention, if the specific conditions are not specified, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. All raw materials and reagents used without specifying the manufacturer are conventional products that can be purchased from the market.

[0043] Example 1

[0044] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0045] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 3.00 g of vanillin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0046] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0047] Example 2

[0048] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0049] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0050] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0051] Example 3

[0052] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0053] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 5.00 g of coumarin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0054] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 3 is that coumarin is not added and the heating and stirring in this step are omitted. All other raw materials and steps are exactly the same as those in Example 3.

[0057] Example 4

[0058] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0059] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (50.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0060] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0061] Example 5

[0062] The difference between this example and Example 4 is that the humic acid is changed to 100.0 mg / ml, and all other raw materials and steps are exactly the same as those in Example 4.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 4 is that humic acid is not added and the heating and stirring of this step are omitted. All other raw materials and steps are exactly the same as those in Example 4.

[0065] Example 6

[0066] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0067] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.00 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0068] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0069] Example 7

[0070] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0071] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0072] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.50 g), dried at 50°C for 36 h, and the film was manually peeled off from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and completely dried at 50°C for 4 h to obtain a film.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 7 is that calcium nitrate is not added, and all other raw materials and steps are exactly the same as those in Example 7.

[0075] Comparative Example 4 (Compared with Examples 2 and 8, the amount of expanded bagasse used was too little, and the amount of phosphate rock powder used was too much)

[0076] (1) First, 1.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 40.0 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0077] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0078] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0079] Example 8

[0080] The difference between this embodiment and comparative example 4 is that the amount of expanded bagasse is increased to 5.00 g, and all other raw materials and steps are exactly the same as those in comparative example 4.

[0081] Example 9

[0082] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 10.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0083] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0084] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0085] Comparative Example 5

[0086] The difference between this comparative example and Example 9 is that phosphate rock powder is not added, and all other raw materials and steps are exactly the same as those in Example 9.

[0087] Example 10

[0088] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0089] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 70°C and stir for 5 h. Add 2.50 g of vanillin to the polyvinyl alcohol solution, heat at 80°C and stir for 0.5 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 1 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 60°C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80°C and stir for 1 h.

[0090] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0091] Example 11

[0092] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in an 80°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0093] (2) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 100 ° C and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 70 ° C and stir for 1 h. Add 10 ml of humic acid (25.0 mg / ml) solution (solvent is dimethyl sulfoxide) dropwise into the above solution, stir for 1 h and then ultrasonicate for 0.5 h. Add EDC / NHS (0.10 g each, 4.24 mmol / L each) aqueous solution to the above mixed solution, heat at 90 ° C and stir for 6 h. Finally, add 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1), heat at 80 ° C and stir for 1 h.

[0094] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 48 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0095] Comparative Example 6 (Compared with Example 2, the order of adding expanded bagasse and phosphate rock powder is different)

[0096] (1) Dissolve 5.00 g of polyvinyl alcohol in 100 mL of dimethyl sulfoxide, heat at 90°C, and stir for 5 h. Add 2.50 g of coumarin to the polyvinyl alcohol solution, heat at 80°C, and stir for 0.5 h. Add 10 ml of humic acid solution (25.0 mg / ml) (solvent: dimethyl sulfoxide) dropwise to the above solution, stir for 1 h, and then sonicate for 0.5 h. Add an aqueous solution of EDC / NHS (0.10 g each, 4.24 mmol / L each) to the above mixed solution, heat at 60°C, and stir for 6 h.

[0097] (2) Add 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) and 4.00 g of phosphate rock powder; finally, add 1.50 g of sodium alginate, heat at 80°C and stir for 1 hour.

[0098] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0099] Comparative Example 7 (Compared with Example 2, prepared using a one-pot method)

[0100] (1) First, 2.00 g of puffed bagasse (neutral detergent fiber content of 63.56%, acid detergent fiber content of 57.28%, acid detergent lignin content of 15.3%, crude protein of 3.23%) was dispersed in 50 mL of pure water, and then 4.00 g of phosphate rock powder was added and mixed. The mixture was heated in a 50°C water bath with stirring for 1 h to allow the puffed bagasse to absorb the phosphate rock powder.

[0101] (2) In a one-pot method, 5.00 g of polyvinyl alcohol, 2.50 g of coumarin, 10 mL of humic acid solution (25.0 mg / mL) (solvent: dimethyl sulfoxide), and 0.10 g of each EDC / NHS solution (4.24 mmol / L each) were dissolved in 100 mL of dimethyl sulfoxide, heated at 60°C, and stirred for 6 h. Finally, 1.50 g of sodium alginate and the mixed solution of expanded bagasse adsorbed phosphate rock prepared in step (1) were added, and heated at 80°C and stirred for 1 h.

[0102] (3) The mixed solution was introduced into a glass dish (20 cm in diameter) containing 15 mL of an aqueous solution of calcium nitrate (containing 0.75 g) and dried at 50°C for 36 h. The film was then manually peeled from the glass dish. The film was dialyzed in deionized water for 36 h to remove unreacted raw materials. The film was dried at room temperature for 24 h and then completely dried at 50°C for 4 h to obtain a film.

[0103] The mechanical properties of the degradable bagasse mulch film loaded with phosphate rock prepared above were tested according to the GB / T35795-2017 standard. The results are shown in Table 1 below.

[0104] Table 1

[0105] project Longitudinal elongation at break / % Transverse tensile strength / MPa Example 2 451 67 Example 3 455 66 Comparative Example 1 105 16 Example 4 449 68 Example 5 453 66 Comparative Example 2 380 29 Example 6 451 63 Example 7 389 49 Comparative Example 3 226 36 Example 8 448 62 Example 9 446 66 Comparative Example 6 201 35 Comparative Example 7 96 20

[0106] According to the data in Table 1, changes in the content of coumarin (Example 2, Example 3 and Comparative Example 1), humic acid (Example 2, Example 4, Example 5 and Comparative Example 2), and calcium ions (Example 2, Example 7 and Comparative Example 3) have a significant effect on the mechanical properties of the mulch film. The carbonyl group in coumarin is cross-linked with the aliphatic hydroxyl group in the PVA chain through hydrogen bonds, while humic acid forms a hydrogen bond network with the PVA chain through the phenolic hydroxyl group and aliphatic hydroxyl group in its molecule. In addition, calcium ions can coordinate with the phenolic hydroxyl group, carboxylic acid group of humic acid and the carbonyl group of coumarin. Therefore, the formation of the mulch film mainly depends on the synergistic effect of hydrogen bonds and coordination interactions.

[0107] The degradable bagasse mulch film loaded with phosphate rock prepared above was applied to soil grown for soybean cultivation. A layer of mulch, 11.78 μm thick, was laid on the soil surface. Potted plants were then tested for degradation time, soil organic matter content, and available phosphorus content after film degradation. The results are shown in Table 2 below.

[0108] Table 2

[0109]

[0110]

[0111] As shown in Table 2, the mulch without humic acid (Comparative Example 2) degraded particularly quickly, completely degrading by 12 days. This also negatively impacted the increase in available phosphorus and organic matter. Compared to the phosphate rock mulch group, both available phosphorus and organic matter content were increased in the mulch mulch group. Variations in the bagasse content (Examples 2, 8, and Comparative Example 4) significantly impacted the increase in available phosphorus.

[0112] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a degradable bagasse mulch film loaded with phosphate rock powder, characterized in that: The following steps are involved: (1) mixing expanded bagasse, phosphate rock and water, heating and stirring to obtain an expanded bagasse solution adsorbing phosphate rock; (2) After adding coumarin and / or vanillin to a polyvinyl alcohol solution and heating for reaction, adding a humic acid solution and reacting, then adding a crosslinker solution and heating for reaction, then adding sodium alginate and the expanded bagasse solution adsorbed with phosphate rock powder in step (1) and mixing them uniformly, finally adding a calcium nitrate solution and mixing them uniformly, drying to form a film, dialyzing, and drying to obtain a degradable bagasse mulch film loaded with phosphate rock powder.

2. The method for preparing a degradable bagasse mulch film loaded with phosphate rock according to claim 1, characterized in that: The mass ratio of the expanded bagasse, phosphate rock and water in step (1) is 1-10:1-10:1-200; And / or, the mass ratio of coumarin and / or vanillin in step (2) to polyvinyl alcohol, humic acid, cross-linking agent, sodium alginate, and calcium nitrate is 1.5-10:2-25:0.25-1:0.1-1:1-1.5:0.5-0.75; And / or, the mass ratio of the sodium alginate and the expanded bagasse solution adsorbing phosphate rock powder in step (2) is 1.5-10:40-300.

3. The method for preparing a degradable bagasse mulch film loaded with phosphate rock according to claim 2, characterized in that: The mass ratio of the expanded bagasse, phosphate rock and water in step (1) is 2-5:4-10:50; And / or, the mass ratio of coumarin and / or vanillin in step (2) to polyvinyl alcohol, humic acid, cross-linking agent, sodium alginate, and calcium nitrate is 2.5-5:5:0.25-1:0.2:1-1.5:0.5-0.75; And / or, the mass ratio of the sodium alginate and the expanded bagasse solution adsorbing phosphate rock powder in step (2) is 1-1.5:56-62.

4. The method for preparing a degradable bagasse mulch film loaded with phosphate rock according to claim 1 or 2, characterized in that: The expanded bagasse in step (1) has a neutral detergent fiber content of 62.37-82.37%, an acid detergent fiber content of 47.28-67.28%, an acid detergent lignin content of 5.3-25.3%, and a crude protein content of 2.23-4.23%; And / or, the heating and stirring temperature in step (1) is 40-60° C., and the stirring time is 0.5-2 h.

5. The method for preparing a degradable bagasse mulch film loaded with phosphate rock according to claim 1 or 2, characterized in that: The crosslinking agent in the crosslinking agent solution of step (2) is 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide in a mass ratio of 1:1; and / or, the total concentration of the cross-linking agent in the cross-linking agent solution in step (2) is 4 to 12 mmol / L; And / or, after adding the crosslinking agent solution in step (2), heating the reaction at 40-60° C. for 5-12 hours.

6. The method for preparing a degradable bagasse mulch film loaded with phosphate rock according to claim 1 or 2, characterized in that: The coumarin and / or vanillin in step (2) is added to a polyvinyl alcohol solution and heated at 70-95° C. for reaction for 0.5-2 h; And / or, after adding the humic acid solution in step (2), stirring the mixture for 0.5 to 2 hours and then ultrasonicating the mixture for 0.5 to 1 hour; And / or, in step (2), sodium alginate and the expanded bagasse solution adsorbed with phosphate rock powder in step (1) are added and heated and stirred at 70-95° C. for 0.5-3 h.

7. The method for preparing a degradable bagasse mulch film loaded with phosphate rock according to claim 1 or 2, characterized in that: In the humic acid solution of step (2), the mass ratio of humic acid to solvent is 1-10:1-200; and / or, in the polyvinyl alcohol solution of step (2), the mass ratio of polyvinyl alcohol to solvent volume is 1-10 g:1-200 mL; And / or, the mass ratio of calcium nitrate to water in the calcium nitrate solution of step (2) is 0.5-5:10-50.

8. The method for preparing a degradable bagasse mulch film loaded with phosphate rock according to claim 1 or 2, characterized in that: The drying temperature of the film in step (2) is 40 to 65° C. and the drying time is 24 to 72 hours; And / or, the dialysis time in step (2) is 24 to 48 hours; And / or, the drying after dialysis in step (2) refers to drying at room temperature for 24 to 48 hours and then drying at 40 to 60° C. for 2 to 7 hours.

9. A degradable bagasse mulch film loaded with phosphate rock powder, prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the degradable bagasse mulch film loaded with phosphate rock powder as claimed in claim 9.

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