Method for degrading polyolefin plastic and application thereof

Abstract

The invention discloses a method for degrading polyolefin plastics and application thereof. The method for degrading the polyolefin plastics comprises the following steps: 1) putting polyolefin plastic wastes in an illumination and ozone-containing atmosphere for illumination-ozone synergistic pretreatment to obtain pretreated polyolefin plastic wastes; and 2) adding the pretreated polyolefin plastic waste into soil for biodegradation. According to the method, illumination-ozone synergistic pretreatment and biodegradation are combined, polyolefin plastics can be rapidly and efficiently degraded, and the method is easy to operate, economical, efficient and suitable for recycling and regenerating plastic waste in the natural environment.

Description

Technical Field

[0001] The invention relates to the technical field of plastic waste recycling and regeneration, and in particular to a method for degrading polyolefin plastics and application thereof. Background Art

[0002] Plastics have the advantages of light weight, good weather resistance, good thermal stability, excellent insulation performance, strong plasticity, and low manufacturing cost, and have been widely used in various fields. Polyolefin plastics (such as PE, PP) are the most widely used plastics. About 77% of plastic products in the world are made of polyolefin plastics, but the treatment and disposal of waste polyolefin plastic products has become a major problem. At present, most of the waste plastics are incinerated or directly landfilled, and only 6% to 26% are recycled. Biodegradation is one of the methods for recycling waste plastics, which has good practical application prospects. The recycling of biodegradable plastics can effectively reduce energy consumption and carbon dioxide production from the perspective of the entire life cycle. However, the direct degradation of polyolefin plastics by microorganisms in the natural environment has the problem of very slow degradation speed, which is difficult to meet the requirements of practical applications.

[0003] Therefore, developing a method that can quickly and efficiently biodegrade polyolefin plastics is of great significance for achieving plastic recycling and circular bioeconomy. Summary of the invention

[0004] The purpose of the present invention is to provide a method for degrading polyolefin plastics and application thereof.

[0005] The technical solution adopted by the present invention is:

[0006] A method for degrading polyolefin plastics comprises the following steps:

[0007] 1) placing polyolefin plastic waste in a light-containing ozone atmosphere for light-ozone synergistic pretreatment to obtain pretreated polyolefin plastic waste;

[0008] 2) Add the pretreated polyolefin plastic waste into the soil for biodegradation.

[0009] Preferably, the polyolefin plastic waste in step 1) is at least one of polyethylene waste and polypropylene waste.

[0010] Preferably, the light source intensity of step 1) is 30W / m 2 ~60W / m 2 .

[0011] Preferably, the ozone concentration of the ozone-containing atmosphere in step 1) is 200 ppm to 2000 ppm.

[0012] Preferably, the time of the light-ozone synergistic pretreatment in step 1) is 12 h to 24 h.

[0013] Preferably, in step 2), the mass ratio of the pretreated polyolefin plastic waste to soil is 0.0002 to 0.02:1.

[0014] Preferably, the indigenous bacteria in the soil in step 2) include at least one of Nitrospira, Sphingomonas, Bradyrhizobium and Rhizobium.

[0015] Preferably, the indigenous fungi in the soil of step 2) include at least one of Agaricus fragilis, Ascomycetes, Mortierella, Debaryomyces, and Metarhizium.

[0016] Preferably, the biodegradation time in step 2) is 20 to 45 days.

[0017] The method for degrading polyolefin plastics as described above is used for recycling plastic waste in the natural environment.

[0018] The beneficial effects of the present invention are as follows: the present invention combines light-ozone synergistic pretreatment with biodegradation, can quickly and efficiently degrade polyolefin plastics, is simple to operate, economical and efficient, and is suitable for recycling plastic waste in the natural environment.

[0019] Specifically:

[0020] 1) The method for degrading polyolefin plastics of the present invention has the characteristics of simple operation and good degradation effect, greatly shortens the degradation time of plastic waste, is suitable for recycling plastic waste in the natural environment, and has broad application prospects;

[0021] 2) The method for degrading polyolefin plastics of the present invention has the characteristics of low processing cost and simple and direct technology, thereby reducing the recycling cost of plastics;

[0022] 3) The method for degrading polyolefin plastics of the present invention directly utilizes indigenous microorganisms in the soil to biodegrade plastics without the need for adding external bacterial agents, thereby further reducing the recycling cost of plastics;

[0023] 4) The method for degrading polyolefin plastics of the present invention has the characteristics of easy control of the operation process and no need to use toxic and harmful raw materials, and has a good application prospect in the field of plastic waste recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the SEM image of the biodegradable PE plastic film in Example 1.

[0025] Figure 2This is the SEM image of the biodegraded PE plastic film in Comparative Example 1.

[0026] Figure 3 This is the SEM image of the biodegraded PE plastic film in Comparative Example 2.

[0027] Figure 4 This is the SEM image of the biodegraded PE plastic film in Comparative Example 3.

[0028] Figure 5 FTIR graphs of the biodegraded PE plastic films in Example 1 and Comparative Examples 1-3.

[0029] Figure 6 It is the XPS graph of the biodegraded PE plastic film in Example 1 and Comparative Examples 1-3.

[0030] Figure 7 This is the SEM image of the biodegradable PP plastic film in Example 2.

[0031] Figure 8 This is the SEM image of the biodegraded PP plastic film in Comparative Example 4.

[0032] Fig. 9 This is the SEM image of the biodegraded PP plastic film in Comparative Example 5.

[0033] Fig.10 This is the SEM image of the biodegraded PP plastic film in Comparative Example 6.

[0034] Fig.11 FTIR graphs of the biodegraded PP plastic films in Example 2 and Comparative Examples 4-6.

[0035] Fig.12 It is the XPS graph of the biodegraded PP plastic film in Example 2 and Comparative Examples 4-6. DETAILED DESCRIPTION

[0036] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0037] Note:

[0038] The soil in the embodiments and comparative examples was collected from Panyu District, Guangzhou City. The basic parameters of the soil (tested by industry standard methods) are as follows: total nitrogen content is 1.9 g / kg, total phosphorus content is 1.8 g / kg, total potassium content is 18.4 g / kg, alkaline nitrogen content is 157.6 mg / kg, effective phosphorus content is 215.8 mg / kg, available potassium content is 254.5 mg / kg, and organic matter content is 33.8 g / kg. The indigenous microbial community structure of the soil obtained by 16S rRNA sequencing and ITS sequencing is as follows: indigenous bacteria mainly include Nitrospira, Sphingomonas, Bradyrhizobium, Rhizobium, etc.; indigenous fungi mainly include Agaricus fragilis, Ascomycetes, Mortierella, Debaryomyces, Metarhizobium, etc.

[0039] The soils in the examples and comparative examples were all pre-stabilized as follows: the soils were placed in flower pots, the water content of the soils was adjusted by watering to 60% of the maximum field water holding capacity, and the soils were cultured for one week.

[0040] Embodiment 1:

[0041] A method for degrading polyolefin plastics, comprising the following steps:

[0042] 1) Place the PE plastic film in a quartz glass tube and introduce ozone for 24 hours of light-ozone synergistic pretreatment while irradiating the film. The light source intensity is 60W / m 2 , the ozone concentration is 2000ppm, and a pretreated PE plastic film is obtained;

[0043] 2) The pretreated PE plastic film was added to the soil for 45 days of biodegradation, and the mass ratio of the pretreated PE plastic film to the soil was 0.0002:1.

[0044] Comparative Example 1:

[0045] A method for degrading polyolefin plastics, comprising the following steps:

[0046] PE plastic film (without pretreatment) was added to soil for 45 days of biodegradation, and the mass ratio of PE plastic film to soil was 0.0002:1.

[0047] Comparative Example 2:

[0048] A method for degrading polyolefin plastics, comprising the following steps:

[0049] 1) Place the PE plastic film in a quartz glass tube for 24 hours of light pretreatment, and the light source intensity is 60W / m 2 , obtaining a pretreated PE plastic film;

[0050] 2) The pretreated PE plastic film was added to the soil for 45 days of biodegradation, and the mass ratio of the pretreated PE plastic film to the soil was 0.0002:1.

[0051] Comparative Example 3:

[0052] A method for degrading polyolefin plastics, comprising the following steps:

[0053] 1) placing a PE plastic film in a quartz glass tube, introducing ozone for 24 hours, with an ozone concentration of 2000 ppm, to obtain a pretreated PE plastic film;

[0054] 2) The pretreated PE plastic film was added to the soil for 45 days of biodegradation, and the mass ratio of the pretreated PE plastic film to the soil was 0.0002:1.

[0055] Performance Test:

[0056] 1) The scanning electron microscope (SEM) images of the biodegradable PE plastic films in Example 1 and Comparative Examples 1 to 3 are as follows: Figures 1 to 4 shown.

[0057] Depend on Figures 1 to 4 It can be seen that after biodegradation, the pretreated PE plastic film in Example 1 (after light-ozone synergistic pretreatment) has dense and deep grooves on the surface of the film, and the biodegradation effect is significantly better than that of Comparative Examples 1 to 3, indicating that light-ozone synergistic pretreatment promotes the natural degradation of the plastic film.

[0058] 2) The infrared spectra (FTIR) of the biodegradable PE plastic films in Example 1 and Comparative Examples 1 to 3 are as follows: Figure 5 shown.

[0059] Depend on Figure 5 It can be seen that: after the pretreated PE plastic film (which underwent light-ozone synergistic pretreatment) in Example 1 was biodegraded, C=O bonds appeared, indicating that the biological oxidation effect was enhanced during the natural degradation process.

[0060] 3) The degradation rate of the PE plastic film in Example 1 and Comparative Examples 1 to 3 was tested, and the degradation rate calculation formula was as follows: Degradation rate (%) = (initial plastic film mass - plastic film mass after biodegradation treatment) / initial plastic film mass × 100%, and the O / C ratio of the biodegraded PE plastic film in Example 1 and Comparative Examples 1 to 3 was tested, and the O / C ratio was determined by X-ray photoelectron spectroscopy (XPS). The degradation rate test results are shown in Table 1, the O / C ratio test results are shown in Table 2, and the XPS graph is shown in Table 2. Figure 6 As shown:

[0061] Table 1 Degradation rate of PE plastic film

[0062]

[0063] Table 2 O / C ratio of biodegradable PE plastic film

[0064]

[0065] From Table 1, Table 2 and Figure 6 It can be seen that the degradation of PE plastic film without pretreatment is very slow, the degradation rate is very low, only 0.04%, and the O / C ratio is also low, only 23.81%; after light pretreatment alone, the degradation rate is slightly enhanced to 0.12%, and the O / C ratio is 19.35%; after ozone pretreatment alone, the degradation rate increased significantly, reaching 9.40%, and the O / C ratio increased to 39.69%; after light and ozone synergistic pretreatment, the degradation rate increased significantly, reaching 41.91%, and the O / C ratio reached 46.83%.

[0066] In summary, the present invention adopts light and ozone synergistic treatment and then performs biodegradation treatment. While being simple to operate and low in cost, it significantly improves the natural degradation efficiency of polyolefin plastics. Compared with plastics without pretreatment, the biodegradation rate of polyethylene plastics is increased by thousands of times, which effectively solves the problem of slow degradation of difficult-to-degrade plastics in the natural environment, and is of great significance for realizing the circular bioeconomy of polyolefin plastics.

[0067] Embodiment 2:

[0068] A method for degrading polyolefin plastics, comprising the following steps:

[0069] 1) Place the PP plastic film in a quartz glass tube and introduce ozone for 24 hours of light-ozone synergistic pretreatment while irradiating it. The light source intensity is 60W / m 2 , the ozone concentration is 2000ppm, and the pretreated PP plastic film is obtained;

[0070] 2) The pretreated PP plastic film was added to the soil for 45 days of biodegradation, and the mass ratio of the pretreated PP plastic film to the soil was 0.0002:1.

[0071] Comparative Example 4:

[0072] A method for degrading polyolefin plastics, comprising the following steps:

[0073] PP plastic film (without pretreatment) was added to soil for 45 days of biodegradation, and the mass ratio of PP plastic film to soil was 0.0002:1.

[0074] Comparative Example 5:

[0075] A method for degrading polyolefin plastics, comprising the following steps:

[0076] 1) Place the PP plastic film in a quartz glass tube for 24 hours of light pretreatment, the light source intensity is 60W / m 2 , obtaining a pretreated PP plastic film;

[0077] 2) The pretreated PP plastic film was added to the soil for 45 days of biodegradation, and the mass ratio of the pretreated PP plastic film to the soil was 0.0002:1.

[0078] Comparative Example 6:

[0079] A method for degrading polyolefin plastics, comprising the following steps:

[0080] 1) placing a PP plastic film in a quartz glass tube, introducing ozone for 24 hours, and performing ozone pretreatment at an ozone concentration of 2000 ppm to obtain a pretreated PP plastic film;

[0081] 2) The pretreated PP plastic film was added to the soil for 45 days of biodegradation, and the mass ratio of the pretreated PP plastic film to the soil was 0.0002:1.

[0082] Performance Test:

[0083] 1) The SEM images of the biodegradable PP plastic films in Example 2 and Comparative Examples 4 to 6 are as follows: Figures 7-10 shown.

[0084] Depend on Figures 7-10 It can be seen that after biodegradation, the pretreated PP plastic film in Example 2 (which underwent light-ozone synergistic pretreatment) had dense and deep grooves on the surface of the film, and the biodegradation effect was significantly better than that of Comparative Examples 4 to 6, indicating that light-ozone synergistic pretreatment promoted the natural degradation of the plastic film.

[0085] 2) The FTIR images of the biodegradable PP plastic films in Example 2 and Comparative Examples 4 to 6 are as follows: Fig.11 shown.

[0086] Depend on Fig.11 It can be seen that: after biodegradation, C=O bonds appeared in the pretreated PP plastic film (which underwent light-ozone synergistic pretreatment) in Example 2, indicating that the biological oxidation effect was enhanced during the natural degradation process.

[0087] 3) The degradation rate of the PP plastic film in Example 2 and Comparative Examples 4 to 6 was tested, and the O / C ratio of the biodegraded PP plastic film in Example 2 and Comparative Examples 4 to 6 was tested. The O / C ratio was determined by XPS. The degradation rate test results are shown in Table 3, the O / C ratio test results are shown in Table 4, and the XPS graph is shown in Table 5. Fig.12 As shown:

[0088] Table 3 Degradation rate of PP plastic film

[0089]

[0090] Table 4 O / C ratio of biodegradable PP plastic film

[0091]

[0092] From Table 3, Table 4 and Fig.12 It can be seen that the degradation of PP plastic film without pretreatment is very slow, the degradation rate is very low, only 0.01%, and the O / C ratio is also low, only 29.49%; after light pretreatment alone, the degradation rate is slightly enhanced to 0.16%, and the O / C ratio is 34.33%; after ozone pretreatment alone, the degradation rate increases significantly, reaching 9.21%, and the O / C ratio increases to 43.50%; after light and ozone synergistic pretreatment, the degradation rate increases significantly, reaching 45.85%, and the O / C ratio reaches 50.19%.

[0093] In summary, the present invention adopts light and ozone synergistic treatment, and then performs biodegradation treatment. While being simple to operate and low in cost, it significantly improves the natural degradation efficiency of polyolefin plastics. Compared with plastics without pretreatment, the biodegradation rate of polypropylene plastics is increased by thousands of times, which effectively solves the problem of slow degradation of difficult-to-degrade plastics in the natural environment, and is of great significance for realizing the circular bioeconomy of polyolefin plastics.

[0094] 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 equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for degrading polyolefin plastics, characterized in that: The following steps are involved: 1) placing polyolefin plastic waste in a light-containing ozone atmosphere for light-ozone synergistic pretreatment to obtain pretreated polyolefin plastic waste; 2) Add the pretreated polyolefin plastic waste into the soil for biodegradation.

2. The method for degrading polyolefin plastics according to claim 1, characterized in that: In step 1), the polyolefin plastic waste is at least one of polyethylene waste and polypropylene waste.

3. The method for degrading polyolefin plastics according to claim 1 or 2, characterized in that: Step 1) The light source intensity of the illumination is 30W / m 2 ~60W / m 2 .

4. The method for degrading polyolefin plastics according to claim 1 or 2, characterized in that: The ozone concentration of the ozone-containing atmosphere in step 1) is 200 ppm to 2000 ppm.

5. The method for degrading polyolefin plastics according to claim 1 or 2, characterized in that: The time of the light-ozone synergistic pretreatment in step 1) is 12h to 24h.

6. The method for degrading polyolefin plastics according to claim 1, characterized in that: In step 2), the mass ratio of the pretreated polyolefin plastic waste to soil is 0.0002 to 0.02:

1.

7. The method for degrading polyolefin plastics according to claim 1 or 6, characterized in that: Step 2) The indigenous bacteria in the soil include at least one of Nitrospira, Sphingomonas, Bradyrhizobium, and Rhizobium.

8. The method for degrading polyolefin plastics according to claim 1 or 6, characterized in that: Step 2) The indigenous fungi in the soil include at least one of Agaricus fragilis, Ascomycetes, Mortierella, Debaryomyces, and Metarhizium.

9. The method for degrading polyolefin plastics according to claim 1 or 6, characterized in that: The biodegradation time of step 2) is 20 to 45 days.

10. Use of the method for degrading polyolefin plastics as claimed in any one of claims 1 to 9 for recycling plastic waste in the natural environment.

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