Aging and Adsorption of Polypropylene Microplastics: Key Factors, Models, and Pca-Derived Insights

Abstract

The durability of plastic polymers in the environment and their degradation pathways present a significant global challenge. This study focuses on polypropylene microplastics (MPs) and employs xenon lamp-accelerated aging to simulate the three stages of their aging cycle. Additionally, it investigates the adsorption characteristics of MPs towards heavy metals like Cu and Cr. Comprehensive characterization at each aging stage reveals a dynamic evolution of physical and chemical properties. Notably, time-series principal component analysis (PCA) is introduced to examine the complex relationship between morphology and performance during aging, as well as its impact on heavy metal adsorption. The results indicate that both aging kinetics and adsorption processes conform to logarithmic models, providing a quantitative framework for understanding the environmental behavior of MPs. Statistical analysis reveals that adsorption efficiency is primarily influenced by external factors, including aging time, pH, salinity, humic content, particle size, and specific surface area, while molecular properties (e.g., molecular weight, crystallinity, and the oxygen-to-carbon (O/C) ratio have a lesser impact. In addition to the aging analysis, the study aims to develop a predictive model for MP persistence, aging indicators, and heavy metal adsorption potential, thereby offering a scientific foundation for strategies aimed at environmental protection and pollution prevention.

Keywords: Microplastic pollution, Aging kinetics, Time-series PCA, Adsorption, Polypropylene