Photo-Aging of Biodegradable Polylactic Acid Microplastics

Abstract

Microplastic (MPs) pollution has became a serious issue. Photoaging is one of the main ways to produce MPs. Polylactic acid (PLA) is the most commonly used biodegradable plastic in industry, however, the current reports on the quantitative data of biodegradable PLA MPs produced by photoaging were little known. Therefore, this study selected PLA MPs as representative MPs to explore photoaging of biodegradable MPs. The results showed that PLA MPs were broken by photoaging, resulting in an increase in the total particle numbers and a decrease in average particle size. The numbers of particle in PLA MPs increased from 4.39×106 particles/L to 6.74×106 particles/L, and the average particle size decreased from 22 μm to 17 μm. C=O and C-O on PLA MPs surface were broken, which further confirmed that PLA MPs were degraded and broken after photoaging. This work is helpful to better understand the impact of light on the aging of biodegradable MPs and to assess the environmental risk of biodegradable MPs.