Method for promoting light aging of biodegradable micro-plastic PBAT (poly (butylene adipate-co-terephthalate))

Abstract

The invention relates to the technical field of light aging of micro-plastics, in particular to a method for promoting light aging of biodegradable micro-plastics PBAT (poly (butyleneadipate-co-terephthalate)). According to the specific technical scheme, the method for promoting light aging of the biodegradable micro-plastic PBAT comprises the following steps: washing PBAT-MPs powder for multiple times, drying, mixing with a metal cation solution, continuously stirring for 1 hour at 200rpm under the condition of a constant-temperature darkroom, and then carrying out light-dark alternating treatment. The aging behavior of the micro-plastic in the water environment is researched, and the micro-plastic shows a relatively strong application effect in an actual water body, so that the influence of metal ions in the water body on the aging of the micro-plastic is favorably evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of microplastic photoaging, and in particular to a method for promoting the photoaging of biodegradable microplastics PBAT, and in particular to a method for promoting the photoaging of poly(butylene adipate terephthalate) microplastics (PBAT-MPs) in the presence of copper ions (Cu 2+ ) and calcium ions (Ca 2+ ) Photoaging behavior under two different metal cation systems and their interaction with metal cations. Background Art

[0002] PBAT (polybutylene adipate / terephthalate) plastics are increasingly present in the environment due to their widespread use. PBAT-MPs are primarily derived from the physical, chemical, and biological decomposition of PBAT plastic products. If these microplastics cannot be effectively degraded in a suitable environment, they will persist for a long time and pose a potential threat to the ecosystem. PBAT-MPs may be accidentally ingested by aquatic organisms, causing physical damage and inflammatory reactions in the organisms. PBAT-MPs may also adsorb and accumulate pollutants in the environment, such as heavy metal ions and organic pollutants, further exacerbating their harmful effects. Furthermore, under multiple environmental stresses such as light, heat, and chemical oxidation, the surface physical and chemical properties of PBAT-MPs undergo significant changes, releasing microplastic-derived dissolved organic matter and forming highly reactive functional groups, which in turn affect their adsorption capacity for pollutants and their ecotoxicity.

[0003] Cu 2+ and Ca 2+ Metal ions are common metal ions in the environment. They are widely present in water and soil and are used extensively in many industrial and agricultural activities. This study simulates water environments with varying degrees of contamination by setting up metal ion systems with varying concentrations, allowing for a more comprehensive study of the effects of metal ions on the aging of PBAT-MPs. This study contributes to a deeper understanding of the aging mechanisms of PBAT-MPs under complex environmental conditions, providing a scientific basis for assessing their environmental risks and developing effective pollution control strategies. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a method for promoting the photoaging of biodegradable microplastics PBAT, and studies the Cu 2+ and Ca 2+ Regulation of the photoaging behavior of PBAT microplastics and analysis of the environmental behavior of two metal cations in complex water environments.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] The present invention discloses a method for promoting the photoaging of biodegradable microplastics (PBAT). PBAT-MPs powder is washed multiple times and then dried, mixed with a metal cation solution, stirred continuously at 200 rpm for 1 hour in a constant temperature darkroom, and then subjected to alternating light and dark treatment.

[0007] Preferably, the metal cation solution contains Cu 2+ The concentration of Ca is 0.12-0.1M, 2+ The concentration is 0.1-0.54M.

[0008] Preferably, the constant temperature is 24-26°C.

[0009] Preferably, the mass volume ratio of the PBAT-MPs powder to the metal cation solution is 1:160-200.

[0010] Preferably, the illumination time is greater than or equal to 4 hours.

[0011] The present invention has the following beneficial effects:

[0012] 1. The present invention prepares metal cation solutions with gradient concentrations, covering common concentrations in natural water bodies and concentrations in simulated medium and high pollution environments, which can comprehensively explore the interaction between PBAT-MPs and metal cations under different pollution levels.

[0013] 2. The present invention studies Cu 2+ and Ca 2+ A method to promote the photoaging of PBAT-MPs was developed, and a theoretical basis was provided. PBAT-MPs were photoirradiated in a metal ion solution to cause a certain degree of aging, and the changes in their surface physical and chemical properties were characterized by SEM, FTIR, and XPS.

[0014] 3. This invention studies the aging behavior of microplastics in water environments and demonstrates a strong application effect in actual water bodies, which is conducive to evaluating the impact of metal ions in water bodies on the aging of microplastics. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 PBAT-MPs in deionized water, Cu 2+ System and Ca 2+ Particle size distribution diagram of aging in the system;

[0016] Figure 2 PBAT-MPs in deionized water, Cu 2+ System and Ca 2+ XPS graph of the system after aging for 96h;

[0017] Figure 3This is the FTIR graph of PBAT-MPs aged for 96 hours. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0020] The present invention discloses a method for promoting the photoaging of biodegradable microplastics PBAT. After washing the PBAT-MPs powder multiple times, the powder is screened by standard sieving to obtain a uniform particle size, dried in an oven, and stored in a brown glass bottle away from light. The dried PBAT-MPs powder is mixed with a metal cation solution, stirred continuously at 200 rpm for 1 hour in a dark room at a constant temperature (24-26°C), and then subjected to alternating light and dark treatment, with the illumination time being greater than or equal to 4 hours. The mass volume ratio of the PBAT-MPs powder to the metal cation solution is 1:160-200. The Cu in the metal cation solution is 0.1% to 0.1% 2+ The concentration of Ca is 0.12-0.1M, 2+ The concentration is 0.1-0.54M.

[0021] The present invention will be further described below with reference to specific embodiments.

[0022] Example 1 Photoaging Experiment

[0023] (1) After washing the PBAT-MPs powder several times with deionized water, the powder was sieved using a standard sieve to obtain a sample with a uniform particle size. The sieved sample was dried in a 45°C oven and then transferred to a brown glass bottle and stored in a constant temperature and humidity environment away from light.

[0024] (2) Prepare gradient concentration metal cation solutions: Cu 2+ The system is 0.12mM, 0.36mM and 0.1M, Ca 2+ The systems are 0.1M, 0.3M and 0.54M.

[0025] (3) The experimental device uses a quartz photoreaction tube, and 0.25g of dried PBAT-MPs powder and 50mL of metal cation solution are accurately added to each tube. During the initial mixing stage, the system is continuously stirred at 200rpm for 1 hour under constant temperature (25±0.5℃) dark room conditions to ensure homogenization. High-pressure ultraviolet mercury lamp is used for irradiation. In order to simulate the lighting pattern in the real environment, an alternating cycle mode of 12 hours of light treatment / 12 hours of dark treatment is set. The constant temperature environment of (25±1)℃ is maintained throughout the experiment. To avoid interference from solution evaporation, ultrapure water is added to the initial volume (50±0.5mL) every 4 hours.

[0026] Characterization of PBAT-MPs aging:

[0027] 1. Surface morphology of PBAT-MPs

[0028] Figure 1 Figure 2 shows the particle size distribution of PBAT-MPs after aging in deionized water and the presence of different metal cations. Particles larger than 120 μm account for 80.64% of the original PBAT-MPs. With increasing irradiation time, the fragmentation of the PBAT-MPs increases, reaching an average particle size of approximately 63 μm after 96 hours of irradiation. The particle size distribution data reveals the particle size changes of PBAT-MPs under different treatment conditions. In the metal cation solution, the proportion of large particles shows a significant downward trend, indicating that the presence of metal cations accelerates the aging of PBAT-MPs.

[0029] 2. Composition and changes of PBAT-MPs functional groups

[0030] Figure 2 PBAT-MPs in deionized water, Cu 2+ System and Ca 2+ XPS graph of the system after aging for 96 hours. In the deionized water system, the C1s ( Figure 2 b) The main peaks at 284.8 eV, 286.3 eV, and 288.8 eV correspond to CC, CO, and OC=O, respectively. The peak positions are completely consistent with the C1s spectrum of standard PBAT, indicating that aging in a deionized water environment does not significantly change the carbon bond structure of PBAT.

[0031] O1s( Figure 2 c) The main peaks are located at 531.8eV and 533eV, corresponding to C=O and CO, and the peak positions are consistent with the standard spectrum. Figure 1 This further confirms that the chemical environment of PBAT in the deionized water system remains stable.

[0032] In Cu 2+ In the system, Cu2p( Figure 2d) shows the main peaks at 932.6eV (Cu2p3 / 2) and 952.2eV (Cu2p1 / 2). The positions of these peaks confirm that Cu 2+ ions, indicating that PBAT-MPs 2+ After aging for 96 hours in the ion coexistence system, Cu 2+ Adsorption or binding of ions.

[0033] C1s( Figure 2 e) and O1s( Figure 2 f) shows that the main peak positions and peak intensities in deionized water have changed.

[0034] In Ca 2+ In the system, Ca2p( Figure 2 g) shows that the main peaks are located at 347.4eV (Ca2p3 / 2) and 350.75eV (Ca2p1 / 2). The positions of these peaks confirm that Ca 2+ ions, indicating that PBAT-MPs 2+ After aging for 96 hours in the ion coexistence system, the surface of Ca 2+ Adsorption or binding of ions.

[0035] C1s( Figure 2 h) shows that the main peak position and peak intensity in deionized water have changed. This may be due to the Ca 2+ It interacted with the carbon atoms on the surface of PBAT-MPs and affected the chemical environment of carbon.

[0036] O1s( Figure 2 The peak intensity of i) also changes. This indicates that Ca 2+ The ions interacted with the oxygen atoms in PBAT-MPs and may have formed calcium-oxygen complexes. XPS energy spectrum analysis showed that the surface chemical environment of PBAT-MPs remained stable after aging in deionized water; 2+ and Ca 2+ The presence of metal cations significantly changed the chemical microenvironment on the surface of PBAT-MPs through coordination or complex formation, that is, the presence of metal cations accelerated the photoaging of PBAT.

[0037] Figure 3 The FTIR graph of aged PBAT-MPs is shown in Figure 2. FTIR was used to characterize the changes in functional groups of PBAT-MPs before and after aging. Figure 3 It can be seen that after 96 hours of illumination, Cu 2+ and Ca 2+ In the presence of 3480cm -1 The -OH peak at the 2+ and Ca2+ It forms a coordination bond with the hydroxyl group, changing its vibration characteristics. 1710cm -1 The C=O peak intensity at the position of Cu increases, and light may cause aging of PBAT. The peak intensity change in this area may indicate that light promotes the oxidation transformation of PBAT. FTIR analysis confirms that Cu 2+ and Ca 2+ The chemical environment of the functional groups on the surface of PBAT-MPs is changed by coordination, which promotes the aging of PBAT-MPs; and the concentration of metal ions has a significant effect on the photoaging process of PBAT-MPs.

[0038] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for promoting photoaging of biodegradable microplastics PBAT, characterized by: The PBAT-MPs powder was washed several times and then dried, mixed with a metal cation solution, stirred continuously at 200 rpm for 1 hour in a constant temperature dark room, and then subjected to alternating light and dark treatments.

2. The method for promoting photoaging of biodegradable microplastics PBAT according to claim 1, characterized in that: The metal cation solution Cu 2+ The concentration of Ca is 0.12-0.1M, 2+ The concentration is 0.1-0.54M.

3. The method for promoting photoaging of biodegradable microplastics PBAT according to claim 1, characterized in that: The constant temperature is 24-26°C.

4. The method for promoting photoaging of biodegradable microplastics PBAT according to claim 1, characterized in that: The mass volume ratio of the PBAT-MPs powder to the metal cation solution is 1:160-200.

5. The method for promoting photoaging of biodegradable microplastics PBAT according to claim 1, characterized in that: The illumination time is greater than or equal to 4h.

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