Method for promoting efficient biodegradation of thin film by assisting metabolism of insects through fermentation pretreatment

Abstract

The invention discloses a method for promoting efficient biodegradation of a film by assisting metabolism of insects through fermentation pretreatment, which comprises the following specific steps: 1) firstly mixing bamboo powder cellulose and a coupling agent for powder activation, then adding PBAT resin, uniformly mixing, and carrying out extrusion granulation and film blowing to obtain a BF / PBAT film; 2) dispersing fermentation distiller's yeast in deionized water to obtain fermentation liquor, then spraying the obtained fermentation liquor on the surface of the BF / PBAT thin film, and performing fermentation treatment to obtain a t-BF / PBAT thin film; and (3) feeding tenebrio molitor larvae by using wheat bran, then feeding tenebrio molitor by using a t-BF / PBAT film, and burying tenebrio molitor metabolites in soil. According to the method disclosed by the invention, the BF / PBAT film can be quickly biodegraded, the degradation period is 16-25 weeks, and the BF / PBAT film is nontoxic and harmless to soil after degradation, so that tedious steps and high cost of industrial compost degradation are avoided, and the degradation period is greatly shortened.

Description

Technical Field

[0001] This invention belongs to the field of recycling or processing technology of organic polymer waste, specifically relating to a method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment. Background Technology

[0002] Plastics, as one of the most widely used materials in the 21st century, are favored for their low density and excellent mechanical properties. This has resulted in a large amount of plastic waste, which is not only difficult to degrade in the natural environment, but the microplastics it produces also seriously affect the quality of water and soil, causing great harm to the ecological environment and human health.

[0003] To address the problem of the difficulty in degrading traditional single-use plastics, Yayong Yang (Yayong Yang, etc. Monomer production from supercritical ethanol depolymerization of PET plastic waste using Ni-ZnO / Al2O3 catalyst[J]. Waste Management, 190(2024):318–328) and Shuhan Cai (Shuhan Cai, etc. Highly efficient kilogram-scale mechanochemical catalytic depolymerization of PET polyester waste into reusable monomers[J]. Chemical Engineering) Scholars such as Journal, 500(2024)157131 have made some theoretical progress in using chemical recycling to reuse polyester (PET) waste, but the recycling cost is high. Some zoologists have proposed methods to degrade single-use plastics using insects based on their feeding behavior. For example, CN101717525A discloses a method for degrading polyethylene plastics using Indian meal borer larvae. 150-300 meal borer larvae reduced the weight of a polyethylene plastic bag (about 10g) by only 3.4-11.4% before pupation (45 days). CN110150231A discloses a method for biodegrading plastics using coleopteran insect larvae and their intestinal microorganisms. Each 100 insects can consume up to 2.5g of PE foam plastic, 3.1g of PS foam plastic, or 3.4g of a mixture of the two in a 30-day feeding cycle. CN113854413A discloses a mealworm attractant and a method for using mealworms to degrade plastics. The attractant promotes rapid degradation of polystyrene (PS) by mealworms, significantly improving the degradation rate. However, 30-300g of mealworms are required to degrade 1g of PS plastic. CN116554544A discloses a method to assist insects in degrading plastics, using fast-paced music to stimulate insect hormones and accelerate the degradation of PS. For traditional petroleum-based plastics such as PP, PE, and PS, insect metabolism can indeed play a role in degradation. However, due to the inherent high molecular weight of these plastics, insect degradation efficiency is low, and incomplete degradation leads to questionable environmental impacts of the degradation products. Therefore, this method has not been widely adopted.

[0004] In recent years, plastics such as polybutylene terephthalate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), and polyhydroxyalkanoates (PHA) have gained some market application due to their renewability and biodegradability. Currently, internationally, the treatment of waste biodegradable plastics is generally accomplished through composting. However, composting still has some limitations: to optimize degradation efficiency, a series of complex pretreatment steps are usually required, and the types and quantities of microorganisms involved in the degradation process, as well as environmental conditions (including temperature, humidity, pH, and light intensity), must be strictly controlled; otherwise, the degradation efficiency will be greatly reduced. In addition, composting requires the establishment of dedicated composting treatment facilities. Therefore, the conditions for industrial composting of these plastics are quite demanding, which has become a major obstacle to the widespread application of biodegradable materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a method for promoting the efficient biodegradation of PBAT plastic film through fermentation pretreatment to assist insect metabolism. This method can accelerate the degradation of PBAT plastic film, and the degradation products do not cause any harm to the natural environment.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: A method for promoting efficient biodegradation of membranes by assisting insect metabolism through fermentation pretreatment is provided, and the specific steps are as follows: 1) Preparation of film: First, bamboo cellulose (BF) and coupling agent are added to a high-speed mixer to activate the powder and obtain activated powder. Then, PBAT resin is added and mixed evenly. The resulting mixture is extruded, granulated and blown to obtain BF / PBAT film. 2) Pretreatment for film fermentation: Disperse the fermentation starter in deionized water to obtain fermentation broth, and then spray the obtained fermentation broth onto the surface of the BF / PBAT film obtained in step 1). After fermentation treatment, t-BF / PBAT film is obtained. 3) Degradation of the film: First, feed the mealworm larvae with wheat bran, then feed the mealworms with the t-BF / PBAT film obtained in step 2), and bury the mealworm metabolites in the soil to achieve rapid degradation of the film.

[0007] According to the above scheme, the bamboo cellulose powder in step 1) has a particle size of 2000-2500 mesh; the coupling agent is one or more of the following: silane coupling agent KH-550, KH-560, KH-590, aluminate coupling agent LS-60, DL411, and titanate coupling agent TMC-311W; the mass ratio of bamboo cellulose powder to coupling agent is 1:0.006-0.01.

[0008] According to the above scheme, the process conditions for powder activation in step 1) are: the material temperature of the high-speed mixer is set to 80℃, and the mixing speed is 100rpm for 5 to 30 minutes.

[0009] According to the above scheme, the mass ratio of the activated powder to PBAT resin in step 1) is 0.11 to 0.43:1.

[0010] According to the above scheme, the process conditions for mixing the activated powder and PBAT resin in step 1) are as follows: the material temperature of the high-speed mixer is set to 80-100℃ and the speed is 50-100rpm for 5-10 minutes.

[0011] According to the above scheme, the extrusion granulation process conditions for step 1) are as follows: the obtained mixture is extruded and granulated using a parallel twin-screw extruder, and the extrusion temperature is 130-155℃.

[0012] According to the above scheme, the conditions for step 1) of the blown film process are: blown film is formed using a high-pressure blown film machine, the temperature is 145~165℃, and the blown film ratio is 2~3.

[0013] According to the above scheme, the density of the BF / PBAT film in step 1) is 0.97–1.08 g / cm³. 3 The tensile strength is 24–29 MPa, the elongation at break is 290–360%, the puncture strength is 0.073–0.08 MPa, and the thickness is 15–50 μm.

[0014] According to the above scheme, the fermentation starter in step 2) is a commercially available baijiu starter, whose main microbial groups include yeast and mold.

[0015] According to the above scheme, the concentration of fermentation yeast in the fermentation liquid in step 2) is 0.5-1 wt%.

[0016] According to the above scheme, in step 2), the fermentation liquid is sprayed onto the surface of the BF / PBAT film, with 4 to 22 mL of fermentation liquid sprayed per square meter of BF / PBAT film surface.

[0017] According to the above scheme, the fermentation process conditions in step 2) are: fermentation for 1 to 2 weeks under conditions of 25~32℃ temperature, 50~80% relative humidity, and complete darkness.

[0018] Preferably, the conditions for feeding mealworm larvae with wheat bran in step 3) are as follows: under the conditions of temperature 25~30℃, relative humidity 50~80%, and full-day light, feed mealworm larvae with wheat bran for 1 week until the mealworms grow into active individuals with a body length of 1.0~1.5cm.

[0019] According to the above plan, the conditions for feeding yellow mealworms with t-BF / PBAT film in step 3) are: feeding yellow mealworms for 9 to 18 weeks under conditions of temperature 25~30℃, relative humidity 50~80%, and full-day light.

[0020] According to the above scheme, in step 3), the mealworm metabolites are buried in the soil at a depth of more than 3 cm for a period of more than 4 weeks. The soil type can be red soil, black soil, or brown soil, etc.

[0021] This invention first activates bamboo cellulose powder using a coupling agent. The activated bamboo cellulose powder is then combined with PBAT resin to prepare a BF / PBAT film with excellent physical properties. Subsequently, the film undergoes fermentation pretreatment with fermentation yeast. During this pretreatment, the bamboo cellulose powder serves as a nutrient source for microorganisms in the solid-state fermentation product. After pretreatment, the film's mechanical strength is significantly reduced, and it becomes more attractive to insects, facilitating subsequent feeding by mealworms. Experimental results show that under appropriate process conditions, the fermented t-BF / PBAT film can be consumed in large quantities by mealworms in a short time (100g of pretreated film can be digested by 100 mealworms within 9 weeks). After digestion by the mealworms, the bamboo fiber and PBAT resin are completely degraded into oligomers. Finally, the mealworm metabolites are buried in the soil, where they are rapidly and completely decomposed by soil microorganisms within 4 weeks.

[0022] The beneficial effects of this invention are as follows: The fermentation pretreatment method provided by this invention to assist insect metabolism and promote the efficient biodegradation of film enables BF / PBAT film to biodegrade rapidly, with a degradation cycle of 16 to 25 weeks. After degradation, it is non-toxic and harmless to the soil, thus avoiding the cumbersome steps and expensive costs of industrial composting degradation, and greatly shortening the degradation cycle. Attached Figure Description

[0023] Figure 1 The images show the surface SEM images of the BF / PBAT film (a) prepared in step 1) of Example 1, the product (b) after fermentation for 3 days after spraying fermentation broth onto the surface of the BF / PBAT film in step 2), and the t-BF / PBAT film (c) obtained in step 2). Figure 2 Comparison of mechanical properties of PBAT film, BF / PBAT film obtained in step 1) of Example 1, and t-BF / PBAT film obtained in step 2) of Example 1; Figure 3 Comparison of number-average molecular weight (Mn), weight-average molecular weight (Mw), and Z-average molecular weight (Mz) of PBAT in the mealworm metabolites of Example 1, step 1), step 2), and step 3). Figure 4 The infrared spectra of the PBAT resin used in Example 1, the BF / PBAT film prepared in step 1), and the mealworm metabolites in step 3) are compared. Figure 5 Comparison of the microscopic morphology of mealworm metabolites at different times after burial in Example 1 (ae) and a photograph of mealworm metabolites 4 weeks after burial (f). Figure 6 MS mass spectra of natural soil, soil after 4 weeks of burial of mealworm metabolites, and soil after 8 weeks of burial of mealworm metabolites are shown in Example 1. Figure 7 This is a comparison chart of the inhibition rates of Vibrio fischeri on natural soil, soil after 4 weeks of burying mealworm metabolites, and soil after 8 weeks of burying mealworm metabolites in Example 1. Figure 8 This is a comparison chart of the biodegradation cycles of BF / PBAT films in Examples 1-5. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] The yeast used in this embodiment of the invention is a strong-aroma baijiu yeast provided by Shandong Meixiang Daqu Base, whose main microbial groups include yeast and mold.

[0026] The PBAT resin used in the embodiments and comparative examples of this invention is Zhejiang Huafeng brand, grade PBAT HF101.

[0027] Example 1 A method for promoting efficient biodegradation of membranes by assisting insect metabolism through fermentation pretreatment, comprising the following specific steps: 1) Add aluminate coupling agent DL44 and bamboo cellulose (2500 mesh) to a high-speed mixer. The mass ratio of bamboo cellulose to aluminate coupling agent DL44 is 1:0.01. Set the material temperature of the high-speed mixer to 80℃ and mix at 100 rpm for 5 minutes to obtain activated powder. Then add PBAT resin to the high-speed mixer. The mass ratio of activated powder to PBAT resin is 0.25:1. Set the material temperature of the high-speed mixer to 80℃ and mix at 50 rpm for 5 minutes to obtain a mixture. Subsequently, use a parallel twin-screw extruder (…) The mixture (with an aspect ratio of 48) was extruded and granulated. The extrusion temperatures for each section were set to 130℃, 130℃, 130℃, 140℃, 140℃, 140℃, 150℃, 150℃, 150℃, and 155℃, the main machine speed was 150 rpm, and the feeder speed was 4 rpm. Then, a high-pressure blown film was blown into shape. The temperatures for each zone of the high-pressure blown film were set to 145℃, 155℃, 160℃, and 165℃, the screw speed was 50 rpm, and the blow-up ratio was 2.0, resulting in a BF / PBAT film with a thickness of 22 μm ± 0.2 mm. 2) Spray the fermentation broth (dispersing the yeast in deionized water at a mass concentration of 0.6wt%) onto the surface of the BF / PBAT membrane, about 11mL of fermentation broth per square meter of membrane surface, and then place it in a biochemical incubator (Shanghai Zhicheng Analytical Instrument Manufacturing Co., Ltd., model ZXSD-B1160) and ferment for 1 week at 32℃, 50% relative humidity and in complete darkness to obtain a softened t-BF / PBAT membrane; 3) Place the mealworms in a biochemical incubator and feed them with wheat bran for one week under conditions of 29℃, 70% relative humidity, and full-day light, until the mealworms grow into active individuals with a body length of about 1.5cm. Place 100 of the mealworm larvae in a circular stainless steel sieve (25cm in diameter, 1mm×1mm mesh size), and then place the circular stainless steel sieve in the biochemical incubator. Set the parameters of the biochemical incubator to 29℃, 70% relative humidity, and full-day light. Feed the mealworms small amounts of the t-BF / PBAT film obtained in step 2) multiple times, with a cumulative amount of 300g. Within 17 weeks, 100g of the t-BF / PBAT film will be eaten by the mealworms. Collect the metabolites of the mealworms and bury them in natural soil at a depth of 3cm. The metabolites will be completely decomposed by the soil within 4 weeks.

[0028] In this embodiment, the BF / PBAT film was completely biodegraded within 23 weeks (the entire degradation cycle includes 1 week of fermentation pretreatment, 1 week of wheat bran feeding, 17 weeks of t-BF / PBAT film feeding, and 4 weeks of soil burial).

[0029] The density of the BF / PBAT film prepared in step 1) of this embodiment was tested to be 1.02 g / cm³.3 It has a tensile strength of 27 MPa, an elongation at break of 320%, a puncture strength of 0.078 MPa, and a thickness of 22 μm.

[0030] like Figure 1 The images show SEM images of the BF / PBAT film prepared in step 1) (a), the product after fermentation for 3 days after spraying fermentation broth onto the surface of the BF / PBAT film in step 2) (b), and the t-BF / PBAT film obtained in step 2) (c). As can be seen from the images, with the progress of fermentation, the combined action of various microorganisms leads to the formation of many pores on the film surface, making the film softer and thinner, while preserving its overall structure. After fermentation pretreatment, the BF / PBAT film is more easily consumed by mealworm larvae; simultaneously, the metabolic products produced by microbial erosion attract mealworm larvae, enhancing their feeding desire on the BF / PBAT film.

[0031] like Figure 2 The diagram shows a comparison of the mechanical properties of PBAT film (the PBAT resin used in this embodiment was blown into shape using a high-pressure blown film machine, with the temperature of each zone of the high-pressure blown film machine set at 145-165℃ and the screw speed at 50 rpm), BF / PBAT film obtained in step 1) of this embodiment, and t-BF / PBAT film obtained in step 2) of this embodiment. Figure a shows a comparison of the puncture strength of the three films, and figure b shows a comparison of the tensile strength and elongation at break of the three films. The diagram shows that the PBAT film has a high puncture strength. The presence of bamboo cellulose slightly reduces the puncture strength of the BF / PBAT film, which facilitates the chewing and feeding process of mealworm larvae. It is noteworthy that the t-BF / PBAT film, after being eroded by various microorganisms, exhibits significant mechanical property degradation, with a substantial reduction in tensile strength and elongation at break, and a marked decrease in puncture strength. Under these conditions, mealworm larvae can more easily penetrate and tear the film with their mandibles, thereby accelerating the biodegradation process. This demonstrates that fermentation pretreatment can affect the tearing behavior of mealworms on t-BF / PBAT films. After fermentation pretreatment, the films are more easily torn by mealworms.

[0032] Figure 3This figure compares the number-average molecular weight (Mn), weight-average molecular weight (Mw), and Z-average molecular weight (Mz) of PBAT (r-PBAT) in the BF / PBAT film prepared in step 1), the t-BF / PBAT film obtained in step 2), and the mealworm metabolites in step 3) of this embodiment. As can be seen from the figure, the molecular weight of PBAT in the film changed significantly during different degradation stages. Specifically, Mn decreased sharply from approximately 50,000 to approximately 8,000, changing from a high molecular weight category to a medium molecular weight category; Mw also decreased by about ten times, to approximately 10,000; and Mz decreased by about twenty times. The comparison shows that utilizing mealworm larvae to consume the BF / PBAT film can rapidly reduce the molecular weight of PBAT, thereby greatly reducing the obstacles to subsequent degradation steps. This method of reducing molecular weight is much more effective than directly burying untreated PBAT or BF / PBAT films in the soil.

[0033] Figure 4 The images show a comparison of the infrared spectra of the BF / PBAT film prepared in step 1) (a), the mealworm metabolites in step 3) (b), and the PBAT resin used as raw material (c). It can be seen that the characteristic peaks of curves a and b are almost identical, indicating that the functional groups in the chemical structure of bamboo fiber and PBAT in the BF / PBAT film did not change during the metabolism of mealworm larvae. The peak at 2955 cm⁻¹ in curve c corresponds to the CH vibration of methyl and methylene groups in saturated hydrocarbons; the peak at 1715 cm⁻¹ is attributed to the C=O vibration of the ester group; the peak at 1412 cm⁻¹ corresponds to the CH bending vibration of methyl and methylene groups in saturated hydrocarbons; the peak at 1270 cm⁻¹ indicates the CO vibration of the ester group; and the peak at 730 cm⁻¹ corresponds to the out-of-plane CH bending vibration of the benzene ring. These characteristic peaks highly match the characteristic peaks of the mealworm metabolites, thus confirming that the mealworm metabolites retain their original PBAT chemical structure.

[0034] Figure 5 Figures a, e, and d show the microscopic morphology of mealworm metabolites at different times after burial in this embodiment. Figure a shows mealworm metabolites before burial, figure b shows metabolites after 1 week of burial, figure c shows metabolites after 2 weeks of burial, figure d shows metabolites after 3 weeks of burial, and figure e shows metabolites after 4 weeks of burial. It can be seen that the mealworm metabolites gradually decompose after burial. Figure a shows the microscopic morphology of the metabolites, characterized by a continuous and complete monomeric structure with a distinct layered appearance, uniform texture, and high homogeneity, indicating a consistent overall structure without visible impurities or inhomogeneities. One week after burial in the soil (… Figure 5 (b) The originally sharp, layered structure transforms into irregular, blocky formations, indicating the onset of decomposition and the loss of the original structural integrity. Two weeks later ( Figure 5c) The metabolites underwent significant decomposition, breaking down into large, irregular, coarse clumps. This rapid degradation rate highlights the high sensitivity of the metabolites to environmental factors. Three weeks after burial ( Figure 5 d) The metabolites further decompose into small, coarse fragments, losing their continuity. This indicates that within three weeks, the metabolites are degraded into fine particles that bind with the surrounding soil, demonstrating efficient decomposition. After four weeks ( Figure 5 e) The complete disintegration of metabolites, leaving only broken residues in the soil, indicates that complete decomposition has been achieved through environmental factors and microbial activity. Figure 5 The middle image (f) shows the mealworm metabolites four weeks after burial, indicating that the mealworm metabolites had become homogenized with the soil after four weeks.

[0035] Figure 6 This is a comparison of MS mass spectra of natural soil, soil after 4 weeks of burial of mealworm metabolites, and soil after 8 weeks of burial of mealworm metabolites in this embodiment. No monomers from the degradation of polybutylene terephthalate (PET) were detected in the natural soil. In the soil after 4 weeks of burial of mealworm metabolites, degradation products terephthalic acid and adipic acid were found, but butylene glycol was not detected, possibly due to its low boiling point and subsequent volatilization into the air. Only a small amount of terephthalic acid remained in the soil after 8 weeks of burial of mealworm metabolites, indicating that harmful monomers do not accumulate in the soil but are further degraded over time through environmental factors and microbial activity.

[0036] like Figure 7 The figure shows a comparison of the inhibition rates of Vibrio fischeri on natural soil, soil after 4 weeks of burial of mealworm metabolites, and soil after 8 weeks of burial of mealworm metabolites in this embodiment. Acute toxicity analysis of the soil was performed according to the method in ISO 11348-1:2007, "Determination of the Inhibitory Effect of Water Samples on Vibrio Photoemission (Luminescent Bacteria Test)". Vibrio fischeri was selected as the luminescent bacterium. The inhibition rates of natural soil, soil after 4 weeks of burial of mealworm metabolites, and soil after 8 weeks of burial of mealworm metabolites on Vibrio fischeri were 43.6%, 47.7%, and 45.8%, respectively. It can be seen that the inhibition rate of the luminescent bacteria (Vibrio fischeri) in the soil after 4 weeks of burial of mealworm metabolites was almost identical to that of the natural soil in its initial state, indicating that the biotoxic effect of the decomposition products on soil microorganisms in this embodiment was relatively low and gradually weakened over time.

[0037] Example 2 A method for promoting efficient biodegradation of membranes by assisting insect metabolism through fermentation pretreatment, comprising the following specific steps: 1) Add aluminate coupling agent DL44 and bamboo cellulose (2500 mesh) to a high-speed mixer. The mass ratio of bamboo cellulose to aluminate coupling agent DL44 is 1:0.008. Set the material temperature of the high-speed mixer to 80℃ and mix at 100 rpm for 5 minutes to obtain activated powder. Then add PBAT resin to the high-speed mixer. The mass ratio of activated powder to PBAT resin is 0.43:1. Set the material temperature of the high-speed mixer to 100℃ and mix at 80 rpm for 10 minutes to obtain a mixture. Then extrude and granulate the mixture using a parallel twin-screw extruder. Set the extrusion temperature to 130-155℃, the main extruder speed to 150 rpm, and the feeder speed to 4 rpm. Then blow-form the film using a high-pressure blown film machine. Set the temperature of each zone of the high-pressure blown film machine to 145-165℃, the screw speed to 50 rpm, and the blow-forming ratio to 2.5 to obtain a BF / PBAT film with a thickness of 22 μm ± 0.2 mm. 2) Spray the fermentation liquid (dispersing the yeast in deionized water at a mass concentration of 0.5wt%) onto the surface of the BF / PBAT film, about 22mL of fermentation liquid per square meter of film surface, and then ferment it for 2 weeks in a biochemical incubator at 28℃, 80%RH and in complete darkness to obtain a softened t-BF / PBAT film. 3) Place mealworms in a biochemical incubator and feed the larvae with wheat bran for one week under conditions of 25℃, 50% relative humidity, and full-day light, until the mealworms grow into active individuals with a body length of about 1.5cm. Place 100 mealworm larvae in a circular stainless steel sieve, and then place the circular stainless steel sieve in the biochemical incubator. Set the parameters of the biochemical incubator to 25℃, 50% relative humidity, and full-day light. Feed the mealworms small amounts of the t-BF / PBAT film obtained in step 2) multiple times, with a cumulative amount of 300g. Within 9 weeks, 100g of the t-BF / PBAT film was eaten by the mealworms. Collect the metabolites of the mealworms and bury them in natural soil at a depth of 5cm. Within 4 weeks, the metabolites were completely decomposed by the soil. Acute toxicity analysis of the soil showed that the decomposition products did not cause any harm to the soil.

[0038] In this embodiment, the BF / PBAT film was completely biodegraded within 16 weeks (the entire degradation cycle includes 2 weeks of fermentation, 1 week of wheat bran feeding, 9 weeks of t-BF / PBAT film feeding, and 4 weeks of soil burial).

[0039] The density of the BF / PBAT film prepared in step 1) of this embodiment was tested to be 0.97 g / cm³. 3 It has a tensile strength of 24.7 MPa, an elongation at break of 300%, a puncture strength of 0.074 MPa, and a thickness of 22 μm.

[0040] Example 3 A method for promoting efficient biodegradation of membranes by assisting insect metabolism through fermentation pretreatment, comprising the following specific steps: 1) Add the composite coupling agent (mass ratio of aluminate DL44: titanate TMC-311W = 1:1) and bamboo cellulose (2500 mesh) to a high-speed mixer. The mass ratio of bamboo cellulose to composite coupling agent is 1:0.008. Set the material temperature of the high-speed mixer to 80℃ and mix at 100 rpm for 8 minutes to obtain activated powder. Then add PBAT resin to the high-speed mixer. The mass ratio of activated powder to PBAT resin is 0.25:1. Set the material temperature of the high-speed mixer to 100℃. The mixture was stirred at 80 rpm for 10 minutes to obtain a mixture. Then, the mixture was extruded and granulated using a parallel twin-screw extruder (length-to-diameter ratio = 48). The extrusion temperature was set to 130–155 °C, the main extruder speed was 150 rpm, and the feeder speed was 4 rpm. Then, the mixture was blown into shape using a high-pressure blown film extruder. The temperature of each zone of the high-pressure blown film extruder was set to 145–165 °C, the screw speed was 50 rpm, and the blow-up ratio was 2.0 to obtain a BF / PBAT film with a thickness of 22 μm ± 0.2 mm. 2) Spray the fermentation liquid (disperse the yeast in deionized water at a mass concentration of 1wt%) onto the surface of the BF / PBAT film, about 10mL of fermentation liquid per square meter of film surface, and then ferment it for 2 weeks in a biochemical incubator at 28℃, 70%RH and in complete darkness to obtain a softened t-BF / PBAT film. 3) Yellow mealworms were placed in a biochemical incubator and fed with wheat bran for one week under conditions of 27℃, 60% relative humidity, and full-day light, until the mealworms grew to an active size of about 1.5cm. One hundred mealworm larvae were then placed in a circular stainless steel sieve, which was then placed in the biochemical incubator. The incubator parameters were set to 27℃, 60% relative humidity, and full-day light. The mealworms were fed small amounts of the t-BF / PBAT film obtained in step 2) multiple times, with a cumulative feeding amount of 300g. Within 12 weeks, 100g of the t-BF / PBAT film was consumed by the mealworms. The mealworm metabolites were collected and buried in natural soil at a depth of 4cm. The metabolites were completely decomposed by the soil within 4 weeks. Acute toxicity analysis of the soil showed that the decomposition products did not cause any harm to the soil. In this embodiment, the BF / PBAT film was completely biodegraded within 19 weeks (the entire degradation cycle includes 2 weeks of fermentation, 1 week of wheat bran feeding, 12 weeks of t-BF / PBAT film feeding, and 4 weeks of soil burial).

[0041] The density of the BF / PBAT film prepared in step 1) of this embodiment was tested to be 1.02 g / cm³. 3It has a tensile strength of 26 MPa, an elongation at break of 310%, a puncture strength of 0.077 MPa, and a thickness of 22 μm.

[0042] Example 4 A method for promoting efficient biodegradation of membranes by assisting insect metabolism through fermentation pretreatment, comprising the following specific steps: 1) Add silane coupling agent KH560 and bamboo cellulose (2000 mesh) to a high-speed mixer. The mass ratio of bamboo cellulose to silane coupling agent KH560 is 1:0.006. Set the material temperature of the high-speed mixer to 80℃ and mix at 100 rpm for 30 minutes to obtain activated powder. Then add PBAT resin to the high-speed mixer. The mass ratio of activated powder to PBAT resin is 0.43:1. Set the material temperature of the high-speed mixer to 100℃ and mix at 100 rpm. The mixture was mixed for 8 minutes at a certain speed to obtain a mixture. Then, the mixture was extruded and granulated using a parallel twin-screw extruder (length-to-diameter ratio = 48). The extrusion temperature was set to 130–155℃, the main extruder speed was 150 rpm, and the feeder speed was 4 rpm. Then, the mixture was blown into shape using a high-pressure blown film extruder. The temperature of each zone of the high-pressure blown film extruder was set to 145–165℃, the screw speed was 50 rpm, and the blow-up ratio was 3.0 to obtain a BF / PBAT film with a thickness of 22 μm ± 0.2 mm. 2) Spray the fermentation liquid (dispersing the yeast in deionized water at a mass concentration of 0.7wt%) onto the surface of the BF / PBAT film, about 13mL of fermentation liquid per square meter of film surface, and then ferment it for 1 week in a biochemical incubator at 30℃, 60%RH and in complete darkness to obtain a softened t-BF / PBAT film. 3) Yellow mealworms were placed in a biochemical incubator and fed with wheat bran for one week under conditions of 27℃, 70% relative humidity, and full-day light, until the mealworms grew to an active size of about 1.5cm. One hundred mealworm larvae were then placed in a circular stainless steel sieve, which was then placed in the biochemical incubator. The incubator parameters were set to 27℃, 70% relative humidity, and full-day light. The mealworms were fed small amounts of the t-BF / PBAT film obtained in step 2) multiple times, with a cumulative feeding amount of 300g. Within 14 weeks, 100g of the t-BF / PBAT film was consumed by the mealworms. The mealworm metabolites were collected and buried in natural soil at a depth of 4cm. The metabolites were completely decomposed by the soil within 4 weeks. Acute toxicity analysis of the soil showed that the decomposition products did not cause any harm to the soil. In this embodiment, the BF / PBAT film was completely biodegraded within 20 weeks (the entire degradation cycle includes 1 week of fermentation, 1 week of wheat bran feeding, 14 weeks of t-BF / PBAT film feeding, and 4 weeks of soil burial).

[0043] The density of the BF / PBAT film prepared in step 1) of this embodiment was tested to be 0.97 g / cm³. 3 It has a tensile strength of 24 MPa, an elongation at break of 290%, a puncture strength of 0.073 MPa, and a thickness of 22 μm.

[0044] Example 5 A method for promoting efficient biodegradation of membranes by assisting insect metabolism through fermentation pretreatment, comprising the following specific steps: 1) Add aluminate coupling agent LS-60 and bamboo cellulose (2000 mesh) to a high-speed mixer. The mass ratio of bamboo cellulose to aluminate coupling agent LS-60 is 1:0.008. Set the material temperature of the high-speed mixer to 80℃ and mix at 100 rpm for 5 minutes to obtain activated powder. Then add PBAT resin to the high-speed mixer. The mass ratio of activated powder to PBAT resin is 0.11:1. Set the material temperature of the high-speed mixer to 100℃ and mix at 80 rpm. The mixture was mixed for 8 minutes at a certain speed to obtain a mixture. Then, the mixture was extruded and granulated using a parallel twin-screw extruder (length-to-diameter ratio = 48). The extrusion temperature was set to 130–155℃, the main extruder speed was 150 rpm, and the feeder speed was 4 rpm. Then, the mixture was blown into shape using a high-pressure blown film extruder. The temperature of each zone of the high-pressure blown film extruder was set to 145–165℃, the screw speed was 50 rpm, and the blow-up ratio was 3.0 to obtain a BF / PBAT film with a thickness of 22 μm ± 0.2 mm. 2) Spray the fermentation liquid (dispersing the yeast in deionized water at a mass concentration of 0.5wt%) onto the surface of the BF / PBAT film, about 4mL of fermentation liquid per square meter of film surface, and then ferment it for 2 weeks in a biochemical incubator at 25℃, 50%RH and in complete darkness to obtain a softened t-BF / PBAT film. 3) Yellow mealworms were placed in a biochemical incubator and fed with wheat bran for one week under conditions of 30℃, 80% relative humidity, and full-day light, until the mealworms grew to an active size of about 1.5cm. One hundred mealworm larvae were then placed in a circular stainless steel sieve, which was then placed in the biochemical incubator. The incubator parameters were set to 30℃, 80% relative humidity, and full-day light. The mealworms were fed small amounts of the t-BF / PBAT film obtained in step 2) multiple times, with a cumulative feeding amount of 300g. Within 18 weeks, 100g of the t-BF / PBAT film was consumed by the mealworms. The mealworm metabolites were collected and buried in natural soil at a depth of 3cm. The metabolites were completely decomposed by the soil within 4 weeks. Acute toxicity analysis of the soil showed that the decomposition products did not cause any harm to the soil.

[0045] In this embodiment, the BF / PBAT film was completely biodegraded within 25 weeks (the entire degradation cycle includes 2 weeks of fermentation, 1 week of wheat bran feeding, 18 weeks of t-BF / PBAT film feeding, and 4 weeks of soil burial).

[0046] The density of the BF / PBAT film prepared in step 1) of this embodiment was tested to be 1.08 g / cm³. 3 It has a tensile strength of 29 MPa, an elongation at break of 360%, a puncture strength of 0.08 MPa, and a thickness of 22 μm.

[0047] Figure 8 The graphs show a comparison of the complete biodegradation time of the BF / PBAT films in Examples 1-5. The preparation conditions and fermentation pretreatment time of the BF / PBAT films in different examples significantly affected the efficiency of mealworm ingestion and degradation of the films. Specifically, the properties of the film and the fermentation pretreatment both affect the biting behavior of mealworms, thus influencing the degradation efficiency of the film.

[0048] Comparative Example 1 BF / PBAT films were prepared according to the method in Example 1.

[0049] 100g of the BF / PBAT film prepared in this comparative example (approximately 4.5 square meters in area) was directly buried in natural soil at a depth of 3cm. After 6 months of burial, it was observed that the film was decomposed into fragments of 2-5mm by soil microorganisms, and was not completely degraded. The decomposed fragments were collected, and the mass loss rate of the buried film was measured to be 74.5%.

[0050] The BF / PBAT film prepared in this comparative example was treated using traditional industrial composting methods. Following the standard GB / T19277.1-2011 "Determination of the final aerobic biodegradability of materials under controlled composting conditions – Method for determining the release of carbon dioxide – Part 1: General Method", 100g of the BF / PBAT film (approximately 4.5 square meters in area) was pulverized into fragments and its biodegradability was assessed under simulated industrial composting conditions. The test reactor was filled with uniformly mixed, well-rotted soil (3 months old). The main microbial community in this well-rotted soil consisted of *Geotrophobicus thermophilus* (relative abundance 62.1%), *Bacillus subtilis* (relative abundance 23.7%), mature composting bacteria (<10 mm sieve), and mineral nutrients, with a soil moisture content of 55–60%. Three groups of samples were cultured at 58±2℃ with continuous carbon dioxide-free air circulation (100 ml / min). The cumulative carbon dioxide level was monitored using an infrared gas analyzer (LI-840A) connected to the exhaust port. The percentage of biodegradation (Dt) is calculated using the following formula 1.

[0051] Formula 1 (CO 2 ) T The total amount of carbon dioxide released for each compost container containing the test mixture is expressed in grams per container (g / container). (CO 2 ) B This represents the average amount of carbon dioxide released cumulatively from the blank container, expressed in grams per container (g / container). ThCO 2 The theoretical carbon dioxide release from the test material is expressed in grams per container (g / container).

[0052] According to the above method, the absolute biodegradation rate of the film after 9 months (3 months of fertilizer age and 6 months of industrial composting treatment) is 82.8%.

[0053] Comparative Example 2 BF / PBAT films were prepared according to the method in Example 2.

[0054] Yellow mealworms were placed in a biochemical incubator (same as in Example 1) and fed with wheat bran for one week under conditions of 25°C, 50% relative humidity, and full-day light, until the mealworms grew into active individuals with a body length of about 1.5cm. Then, 100 yellow mealworm larvae were placed in a circular stainless steel sieve, and the circular stainless steel sieve was placed in the biochemical incubator. The parameters of the biochemical incubator were set as 25°C, 50% relative humidity, and full-day light. The yellow mealworms were fed small amounts of BF / PBAT film (without fermentation pretreatment) obtained in this comparative example multiple times, with a cumulative feeding amount of 300g. Within 9 weeks, the yellow mealworms only consumed 20g of BF / PBAT film, and most of the yellow mealworms died naturally, while a small number of yellow mealworms pupated.

[0055] Mealworm metabolites were collected and buried in natural soil at a depth of 2.5 cm. The metabolites were completely decomposed by the soil within 4 weeks. Acute toxicity analysis of the soil showed that the decomposition products did not cause any harm to the soil.

[0056] Compared with Example 2, the BF / PBAT film in this comparative example was fed directly without fermentation, and it was found that the mealworms had a low willingness to gnaw on the unfermented BF / PBAT film.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for promoting efficient biodegradation of films by fermentation pretreatment to assist insect metabolism, characterized in that, The specific steps are as follows: 1) Preparation of film: First, bamboo powder cellulose and coupling agent are added to a high-speed mixer to activate the powder and obtain activated powder. Then, PBAT resin is added and mixed evenly. The resulting mixture is extruded, granulated and blown to obtain BF / PBAT film. 2) Pretreatment for film fermentation: Disperse the fermentation starter in deionized water to obtain fermentation broth, and then spray the obtained fermentation broth onto the surface of the BF / PBAT film obtained in step 1). After fermentation treatment, t-BF / PBAT film is obtained. 3) Degradation of the film: First, feed the mealworm larvae with wheat bran, then feed the mealworms with the t-BF / PBAT film obtained in step 2), and bury the mealworm metabolites in the soil to achieve rapid degradation of the film.

2. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, Step 1) The bamboo cellulose powder has a particle size of 2000-2500 mesh; the coupling agent is one or more of the following: silane coupling agent KH-550, KH-560, KH-590, aluminate coupling agent LS-60, DL411, titanate coupling agent TMC-311W; the mass ratio of bamboo cellulose powder to coupling agent is 1:0.006-0.

01.

3. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, Step 1) The process conditions for powder activation are: the material temperature of the high-speed mixer is set to 80℃, and the mixing speed is 100rpm for 5 to 30 minutes.

4. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, The mass ratio of the activated powder to PBAT resin in step 1) is 0.11 to 0.43:1; the process conditions for mixing the activated powder and PBAT resin in step 1) are: the material temperature of the high-speed mixer is set to 80 to 100°C and the speed is 50 to 100 rpm for 5 to 10 minutes.

5. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, Step 1) Extrusion granulation process conditions: The obtained mixture is extruded and granulated using a parallel twin-screw extruder, with an extrusion temperature of 130-155℃; Step 1) Blown film process conditions: The film is blown into shape using a high-pressure blown film machine, with a temperature of 145-165℃ and a blown ratio of 2-3.

6. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, Step 1) The density of the BF / PBAT film is 0.97–1.08 g / cm³. 3 The tensile strength is 24–29 MPa, the elongation at break is 290–360%, the puncture strength is 0.073–0.08 MPa, and the thickness is 15–50 μm.

7. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, Step 2) The fermentation starter is a commercially available baijiu starter, whose main microbial groups include yeast and mold; Step 2) The concentration of the fermentation starter in the fermentation liquid is 0.5-1wt%; Step 2) Spray the fermentation liquid onto the surface of the BF / PBAT film, with 4-22mL of fermentation liquid sprayed per square meter of BF / PBAT film surface.

8. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, Step 2) The fermentation process conditions are as follows: fermentation for 1 to 2 weeks at a temperature of 25~32℃, a relative humidity of 50~80%, and under conditions of complete darkness.

9. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, Step 3) The conditions for feeding mealworm larvae with wheat bran are: feed mealworm larvae with wheat bran for 1 week under the conditions of temperature 25~30℃, relative humidity 50~80%, and full-day light, until the mealworms grow into active individuals with a body length of 1.0~1.5cm; Step 3) The conditions for feeding mealworms with t-BF / PBAT film are: feed mealworms for 9~18 weeks under the conditions of temperature 25~30℃, relative humidity 50~80%, and full-day light.

10. The method for promoting efficient biodegradation of films by assisting insect metabolism through fermentation pretreatment according to claim 1, characterized in that, In step 3), the mealworm metabolites are buried in the soil at a depth of more than 3 cm and for a period of more than 4 weeks.

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