Assessing extent of degradation and the potential effects on the quantification of microplastics in the environment

Plastic waste undergoes degradation in natural environments, resulting in changes in size, colour, morphology, and surface chemistry. This study aims to assess the impact of weathering on quantification techniques for microplastics, particularly focusing on Pyrolysis Gas Chromatography/Mass Spectrometry (Pyr-GC/MS). While techniques like FTIR-ATR and SEM have been used to characterize degradation features, limited research has explored their effects on Pyr-GCMS methods and their potential for characterizing microplastic degradation.

Accelerated weathering experiments were conducted on micro-sized polypropylene (PP), high-density polyethylene (HDPE), and polystyrene (PS) beads and fragments for up to 84 days. Analysis techniques including FTIR-ATR, SEM, and DSC were employed to confirm photo-oxidation and mechanical degradation. Preliminary findings suggest that harsh weathering conditions can lead to significant oxidation of plastics, impacting quantification by Pyr-GC/MS. The study highlights the importance of further research into weathering effects to avoid underestimation of microplastic pollution.

Evidence from the study indicates the detection of approximately 86 degradation markers for HDPE and 26 weathering markers for PS that increase over time. These markers show promising potential for establishing relationships between degradation time and Carbonyl Index, a measurement obtained via FTIR analysis. By utilizing these relationships, we can continue our work of developing a method to characterize the degradation of microplastics in the environment. This novel approach offers valuable insights into understanding the degradation processes of microplastics and provides a pathway for assessing environmental impacts more effectively. Overall, this project contributes to understanding the complexities of microplastic degradation and its implications for environmental monitoring and assessment.

Please note this is a PhD student progress review presentation.