Preparation of additive-doped plastic and method for improving white rot fungus degradation

Abstract

The invention discloses a method for preparing a plastic doped with additives and improving the degradation of white rot fungi, and relates to the technical field of solid waste treatment. The invention achieves efficient degradation of plastic by adding additives to plastics, co-culturing the plastics containing additives with white rot fungi in the vegetative stage. The additives include plasticizer dibutyl phthalate, antioxidant 1010 and lubricant stearic acid. Experiments show that after the plastics containing additives are degraded by white rot fungi, obvious cracking occurs on the surface, degradation products are detected in gas phase-mass spectrometry, and molecular weights Mw and Mn are significantly reduced. The method provided by the invention can significantly improve the degradation ability of white rot fungi to plastics, the process is simple and easy, the cost is economical and affordable, and the harmless degradation of plastic pollutants is effectively achieved, which is of great significance to environmental protection.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste treatment, and in particular to a method for preparing additive-doped plastic and improving the degradation of white rot fungi. Background Art

[0002] In recent years, plastic pollution has become increasingly serious. Commonly used polyethylene plastics account for about 30% of plastic solid waste, posing a potential threat to the ecosystem and human health. At present, there are biodegradation, photodegradation, thermal degradation and chemical degradation methods for plastics, but each method has its specific scope of application and limitations. For example, although biodegradation is environmentally friendly, microorganisms cannot effectively degrade plastics, and do not really mineralize plastics into CO2 and H2O on a large scale, and degradation is related to factors such as the type of microorganisms. It can be seen that there are still many difficulties to overcome in the degradation of plastics, and there is currently no mature and effective method that can be widely used in engineering practice. Therefore, it is of great significance to study the degradation of plastics.

[0003] Polystyrene is widely used in packaging materials due to its light weight, high transparency and high electrical insulation performance; polyethylene is often used to manufacture cable protective layers and disposable products due to its good chemical stability and resistance to most acid and alkali corrosion. If plastics are not degraded in the environment for a long time, they will produce more organic pollutants. Therefore, the research on the effective degradation of polyethylene plastics has a positive impact on the environment in terms of reducing carbon emissions and energy consumption. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing additive-doped plastics and improving the degradation of white rot fungi, so as to solve the problems existing in the above-mentioned prior art. According to the method of the present invention, the degradation ability of white rot fungi on plastics can be significantly improved, and white rot fungi can be used to efficiently degrade plastics.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for promoting the degradation of plastics by white rot fungi, comprising the following steps:

[0007] Adding additives to plastics to obtain plastics containing additives;

[0008] Cultivating the white rot fungus in a culture medium until the growth and nutrition stage to obtain a white rot fungus culture;

[0009] co-culturing the plastic containing the additive with the white rot fungus culture to promote the degradation of the plastic by the white rot fungus;

[0010] The additives include plasticizers, antioxidants and lubricants.

[0011] Preferably, the plastic comprises polyethylene or a product containing polyethylene.

[0012] Preferably, the mass ratio of the plasticizer, the antioxidant and the lubricant is (2-4):(1-2):(1-2);

[0013] The plasticizer includes dibutyl phthalate, the antioxidant includes antioxidant 1010, and the lubricant includes stearic acid.

[0014] Preferably, the method of adding additives to plastics comprises: mixing the additives with the plastics at a temperature of 90-110° C. and dissolving them with an organic solvent; wherein the mass ratio of the additives to the plastics is (1-6):10.

[0015] Preferably, the white rot fungus is Phanerochaete chrysosporium, the components of the culture medium include 200 g / L potato extract, 20 g / L glucose, 0.5 g / L magnesium sulfate heptahydrate, 2 g / L potassium dihydrogen phosphate and 20 g / L agar powder, and the pH is 7.5.

[0016] Preferably, the co-culture condition is culturing at 37° C. for more than 50 days.

[0017] The present invention also provides an additive for promoting the degradation of plastics by white rot fungi, the additive comprising a plasticizer, an antioxidant and a lubricant; wherein the mass ratio of the plasticizer, the antioxidant and the lubricant is (2-3):(1-2):(1-2).

[0018] Preferably, the plasticizer includes dibutyl phthalate, the antioxidant includes antioxidant 1010, and the lubricant includes stearic acid.

[0019] The present invention also provides the use of the additive in promoting the degradation of plastics by white rot fungi, wherein the plastics include polyethylene or products containing polyethylene.

[0020] Preferably, the white rot fungus is Phanerochaete chrysosporium.

[0021] The present invention discloses the following technical effects:

[0022] The present invention achieves efficient degradation of plastic by adding additives to plastics, co-culturing the plastics containing additives with white rot fungi in the vegetative stage. Electron microscopic observation found that the surface morphology of the plastic without additives before and after biodegradation was smoother overall; after 50 days of biodegradation co-cultivation, the surface morphology of the plastic containing additives had cleavage changes, and a large number of white rot fungal hyphae were attached. After testing, the molecular weight (Mn and Mw) of the plastics before and after the reaction was greatly reduced, indicating that the plastic molecular chain was broken, and degradation products were detected in the gas phase-mass spectrometry of the plastic containing additives, indicating that the plastic molecules were degraded. Therefore, the method provided by the present invention can significantly enhance the degradation ability of white rot fungi on plastics, the process is simple and easy, the cost is economical and affordable, and the harmless degradation of plastic pollutants is effectively achieved, which is of great significance to environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a diagram of a co-culture experiment of a polyethylene plastic film (sample 2) containing additives and Phanerochaete chrysosporium in Example 1 of the present invention, wherein A is a diagram of a co-culture experiment, and B is a diagram of a plastic film after biodegradation;

[0025] Figure 2 The electron microscope images of the polyethylene plastic film (sample 1) before and after biodegradation in Example 1 of the present invention, wherein A is before biodegradation and B is after biodegradation;

[0026] Figure 3 The electron microscope images of the polyethylene plastic film (sample 2) containing additives in Example 1 of the present invention before and after biodegradation, wherein A is before biodegradation and B is after biodegradation;

[0027] Figure 4 The infrared spectra of Sample 1 and Sample 2 before and after biodegradation in Example 1 of the present invention are shown, wherein Sample 1-Before refers to Sample 1 before degradation; Sample 1-After refers to Sample 1 after degradation; Sample 2-Before refers to Sample 2 before degradation; and Sample 2-After refers to Sample 2 after degradation.

[0028] Figure 5 This is a gas chromatography-mass spectrometry detection result diagram of sample 2 after biodegradation in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] Example 1

[0035] 1. Preparation of plastics containing additives

[0036] Dibutyl phthalate, antioxidant 1010 and stearic acid were mixed in a mass ratio of 2:1:2 to obtain an additive.

[0037] The polyethylene plastic particles were melted at 100° C., stretched on a glass plate, cooled, and separated to obtain a polyethylene plastic film (referred to as Sample 1).

[0038] At 100°C, the additive and polyethylene plastic particles were mixed in a mass ratio of 4:10, dissolved in xylene, stirred to a clear state, and the clear mixture was stretched on a glass plate, cooled, and separated to obtain a polyethylene plastic film containing the additive (referred to as Sample 2).

[0039] Sample 2 was soaked in deionized water for 2 h, rinsed repeatedly, and dried in an oven at 40°C for 24 h.

[0040] 2. Cultivation of Phanerochaete chrysosporium

[0041] (1) Source of strain: China Center for Type Culture Collection (Wuhan), strain number: BKMF-1767, CCTCC, number AF96007.

[0042] (2) The composition of the culture medium is as follows: 200 g / L potato extract, 20 g / L glucose, 0.5 g / L magnesium sulfate heptahydrate, 2 g / L potassium dihydrogen phosphate and 20 g / L agar powder. The pH of the culture medium is 7.5.

[0043] (3) Cultivation method: In a sterile environment, inoculate Phanerochaete chrysosporium on a sterilized culture medium and culture it in a 37°C incubator for 3 days to reach the growth and nutrition stage, at which time the biomass of Phanerochaete chrysosporium is the most abundant, thereby obtaining a culture of Phanerochaete chrysosporium.

[0044] 3. Biodegradation and detection methods

[0045] Samples 1 and 2 (both 3×3 cm) were co-cultured with Phanerochaete chrysosporium culture on a sterilization operation table, with a cycle of 5 days. Observation and detection were carried out after the end of the 10th cycle.

[0046] The surface morphology of the plastic film was observed by electron microscopy, the changes in functional groups were detected by infrared spectroscopy, the degradation products of sample 2 were detected and identified by gas chromatography-mass spectrometry, and the changes in molecular weight of samples 1 and 2 before and after treatment were detected by gel permeation chromatography.

[0047] 4. Test results

[0048] (1) Electron microscopy results

[0049] Comparing the electron microscopic images of the polyethylene plastic film without additives before and after biodegradation, it can be seen that before co-culture, Figure 2 As shown in A, sample 1 has a flat surface. After being co-cultured with Phanerochaete chrysosporium for 50 days, Figure 2 As shown in B, the surface morphology of sample 1 still has no obvious change, indicating that Phanerochaete chrysosporium will not degrade polyethylene plastics.

[0050] Figure 3 A is the surface morphology of sample 2, where a large number of pits can be seen on the surface, and many wrinkled holes are produced. This morphology is more conducive to the attachment of Phanerochaete chrysosporium. After 50 days of co-cultivation, Figure 3As shown in B, sample 2 produced a large number of holes after co-culture with Phanerochaete chrysosporium, and Phanerochaete chrysosporium was observed attached to the inside of the plastic film, indicating that obvious biodegradation occurred.

[0051] (2) Infrared spectrum test results

[0052] like Figure 4 As shown, the infrared spectrum shows that the surface functional groups of the polyethylene plastic film change significantly before and after degradation.

[0053] Compared with Sample 1 (Sample 1-Before), a new group was generated on Sample 2 (Sample 2-Before) with the addition of additives. The new group was at 1705±5cm -1 The highest absorbance is at the region with the highest absorbance. The broad absorbance peak in this region is due to the presence of various oxygen-containing carbonyl (C=O) compounds, including carboxylic acids, ketones and keto acids. The appearance of the carbonyl peak indicates that polar groups have been introduced into the polyethylene main chain, causing the polyethylene plastic to change from hydrophobic to hydrophilic, which is more conducive to the attachment of Phanerochaete chrysosporium to the polyethylene plastic film.

[0054] After co-cultivation with Phanerochaete chrysosporium, the carbonyl (C=O) absorption peak on the infrared spectrum of the biodegraded sample 2 (Sample 2-After) disappeared, indicating that the functional groups of the polyethylene plastic film containing the additive changed and the molecular chain was broken.

[0055] (3) Gas chromatography-mass spectrometry test results

[0056] like Figure 5 As shown in the figure, the gas chromatography-mass spectrometry shows that the polyethylene plastic containing additives is degraded and the polyethylene produces degradation products, which are a series of alkanes with less than 31 carbon atoms. Among them, (1) C 11 H 24 ,(2)C 16 H 34 ,(3)C 21 H 44 ,(4)C 27 H 56 ,(5)C 30 H 62 Corresponding to Figure 5 However, no degradation products were detected in sample 1, which is consistent with the previous electron microscopy observation results and infrared spectroscopy detection results.

[0057] (4) Gel permeation chromatography test results

[0058] Table 1 shows the changes in weight average molecular weight (Mw) and number average molecular weight (Mn) before and after biodegradation of sample 1 and sample 2. As can be seen from Table 1, the addition of additives will reduce the molecular weight of polyethylene plastics because the additives contain self-oxidizable unsaturated groups, which can be used to promote the initial degradation of plastic products.

[0059] At the same time, by comparing the molecular weight of sample 2 before and after degradation, it can be seen that Phanerochaete chrysosporium attaches to sample 2 and degrades the polyethylene plastic film containing additives, which will cause the molecular chain to break and the molecular weight to decrease.

[0060] Table 1 Changes of Mw and Mn before and after biodegradation of sample 1 and sample 2

[0061] sample M Mn Sample 1 before 256217 220575 After sample 1 236002 181807 Sample 2 before 177886 119167 After sample 2 6797 6292

[0062] Example 2

[0063] The difference from Example 1 is that the steps of preparing the plastic containing the additive are:

[0064] Dibutyl phthalate, antioxidant 1010 and stearic acid were mixed in a mass ratio of 3:2:1 to obtain an additive.

[0065] At 110° C., the additive and polyethylene plastic particles were mixed in a mass ratio of 6:10, dissolved in xylene, stirred to a clear state, and the clear mixture was stretched on a glass plate, cooled, and separated to obtain a polyethylene plastic film containing the additive (referred to as Sample 3).

[0066] Example 3

[0067] The difference from Example 1 is that the steps of preparing the plastic containing the additive are:

[0068] Dibutyl phthalate, antioxidant 1010 and stearic acid were mixed in a mass ratio of 4:1:1 to obtain an additive.

[0069] At 90°C, the additive and polyethylene plastic particles were mixed in a mass ratio of 1:10, dissolved in xylene, stirred to a clear state, and the clear mixture was stretched on a glass plate, cooled, and separated to obtain a polyethylene plastic film containing the additive (referred to as Sample 4).

[0070] Example 4

[0071] The gas phase-mass spectrometry detection method and the gel liquid chromatography detection method in Example 1 were used to detect the samples 3 and 4 prepared in Example 2 and Example 3.

[0072] The molecular weight changes of samples 3 and 4 prepared in Examples 2 and 3 are shown in Table 2.

[0073] Table 2 Changes of Mw and Mn before and after biodegradation of samples 1, 3 and 4

[0074] sample M Mn Sample 1 before 256217 220575 After sample 1 236002 181807 Sample 3 before 184962 126214 After sample 3 6849 6325 Sample 4 before 189717 134852 After sample 3 6973 6457

[0075] The degradation products of Sample 3 and Sample 4 prepared in Example 2 and Example 3 are shown in Table 3 and Table 4, respectively.

[0076] Table 3 Biodegradation products of sample 3

[0077]

[0078] Table 4 Biodegradation products of sample 4

[0079]

[0080] In summary, adding additives to polyethylene plastics can change the surface morphology of plastics. According to the infrared spectrum, hydrophilic groups are generated on polyethylene containing additives, and the disappearance of the additive marker functional group carbonyl (C=O) is further verified. The obvious cracks in the plastic film after biodegradation and the attachment and growth of Phanerochaete chrysosporium on polyethylene indicate that the addition of additives promotes the degradation of polyethylene. The most important thing is that the degradation products are detected from the gas phase-mass spectrometry, indicating that the additives promote the breakage of the polyethylene plastic molecular chain and degradation during the biodegradation process; from the molecular weight changes detected by gel permeation chromatography, it can be seen that the additives promote the breakage of the polyethylene plastic molecular chain and the decrease of molecular weight during the biodegradation process.

[0081] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for promoting the degradation of plastics by white rot fungi, characterized in that: The following steps are involved: Adding additives to plastics to obtain plastics containing additives; Cultivating the white rot fungus in a culture medium until the growth and vegetative stage to obtain a white rot fungus culture; co-culturing the plastic containing the additive with the white rot fungus culture to promote the degradation of the plastic by the white rot fungus; The additives include plasticizers, antioxidants and lubricants; Wherein, the mass ratio of the plasticizer, the antioxidant and the lubricant is (2-4):(1-2):(1-2); The plasticizer includes dibutyl phthalate, the antioxidant includes antioxidant 1010, and the lubricant includes stearic acid; The white rot fungus is Phanerochaete chrysosporium, and the preservation number of Phanerochaete chrysosporium is CCTCC NO: AF96007.

2. The method according to claim 1, characterized in that The plastic includes polyethylene or a product containing polyethylene.

3. The method according to claim 1, characterized in that The method of adding additives to plastics comprises: mixing the additives with the plastics at a temperature of 90-110° C. and dissolving them with an organic solvent; wherein the mass ratio of the additives to the plastics is (1-6):

10.

4. The method according to claim 1, characterized in that The components of the culture medium include 200 g / L potato extract, 20 g / L glucose, 0.5 g / L magnesium sulfate heptahydrate, 2 g / L potassium dihydrogen phosphate and 20 g / L agar powder, and the pH value is 7.

5.

5. The method according to claim 1, characterized in that The co-culture conditions are culturing at 37° C. for more than 50 days.

6. Use of an additive in promoting the degradation of plastics by white rot fungi, characterized in that: The additives include plasticizers, antioxidants and lubricants; The mass ratio of the plasticizer, the antioxidant and the lubricant is (2-3):(1-2):(1-2); The plasticizer includes dibutyl phthalate, the antioxidant includes antioxidant 1010, and the lubricant includes stearic acid; The plastic includes polyethylene or a product containing polyethylene; The white rot fungus is Phanerochaete chrysosporium, and the preservation number of Phanerochaete chrysosporium is CCTCC NO: AF96007.

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