College of Marine Ecology and Environment, Shanghai Ocean University, No 999, Huchenghuan Road, Shanghai 201306, PR China.
Research Center for Environmental Functional Materials, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China.
J Hazard Mater. 2023 Apr 15;448:130889. doi: 10.1016/j.jhazmat.2023.130889. Epub 2023 Jan 27.
The COVID-19 pandemic has led to explosive growth in the production and consumption of disposable medical masks, which has caused new global environmental problems due to the improper disposal of these masks and lack of effective mask recycling methods. To reduce the environmental load caused by the inability of synthetic plastics to degrade, polylactic acid (PLA) masks, as a biodegradable environmentally friendly plastic, may become a solution. This study simulated the actual degradation process of new PLA masks in different environments by soaking them in various solutions for 4 weeks and explored the influence of the treated PLA fabric fibers on the growth of winter ryegrass. The results show that the weathering degradation of PLA fibers in water mainly occurs through the hydrolysis of ester bonds, and weathering leads to cheese-like and gully-like erosion on the surface of the PLA fiber fabric layer and finally to fiber fracture and the release of microplastics (MPs). The average number of MPs released within 4 weeks is 149.5 items/piece, the particle size is 20-500 µm (44%), and 63.57% of the MPs are transparent fibers. The outer, middle, and inner layers of weathered PLA masks tend to be hydrophilic and have lower mechanical strength. PLA fibers after different treatment methods affect the growth of winter ryegrass. PLA masks are undoubtedly a greener choice than ordinary commercial masks, but in order to confirm this, the entire degradation process, the final products, and the impact on the environment need to be further studied. In the future, masks may be developed to be made from more environmentally friendly biodegradable materials that can have good protecting effects and also solve the problem of end-of-life recycling. A SYNOPSIS: Simulation of the actual degradation process of PLA masks and exploration of the influence of mask degradation on the growth of winter ryegrass.
新型冠状病毒肺炎疫情导致一次性医用口罩产量和消费量暴增，由于这些口罩的处理不当和缺乏有效的口罩回收方法，造成了新的全球性环境问题。为了减少因合成塑料无法降解而造成的环境负荷，聚乳酸（PLA）口罩作为一种可生物降解的环保塑料，可能成为一种解决方案。本研究通过将新 PLA 口罩浸泡在不同溶液中 4 周来模拟其在不同环境下的实际降解过程，并探索经处理的 PLA 织物纤维对冬黑麦生长的影响。结果表明，PLA 纤维在水中的风化降解主要通过酯键的水解发生，风化导致 PLA 纤维织物层表面出现奶酪状和沟渠状侵蚀，最终导致纤维断裂和微塑料（MPs）的释放。在 4 周内释放的 MPs 的平均数量为 149.5 个/件，粒径为 20-500μm（44%），63.57%的 MPs 为透明纤维。风化 PLA 口罩的外层、中层和内层趋于亲水，机械强度降低。不同处理方法后的 PLA 纤维会影响冬黑麦的生长。PLA 口罩无疑比普通商业口罩更环保，但为了确认这一点，需要进一步研究整个降解过程、最终产物以及对环境的影响。未来，可能会开发出由更环保的可生物降解材料制成的口罩，既能有良好的保护效果，又能解决使用寿命结束后的回收问题。
