We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Influence of aging on stability, aggregation and release of micro and nano-plastics from low-density polyethylene (LDPE) macro-plastics in aquatic environments
Summary
Common plastic bags and packaging (LDPE) release even more tiny nanoplastic particles once they're broken down by sunlight and heat—the kind of aging plastic waste actually undergoes in the environment. This matters because these "weathered" particles behave differently than the pristine, lab-made plastic particles scientists typically study, meaning current research may be underestimating how these particles move through water, accumulate, and potentially end up in the food chain and drinking water we rely on.
The widespread use of plastics has resulted in environmental accumulation and degradation into microplastics (MPs) and nanoplastics (NPs), which persist and pose risks to aquatic ecosystems due to high mobility, bioavailability, and toxicity. In laboratory studies, artificial pristine nanoplastic (NP) proxies, engineered particles with controlled size and composition, are commonly used to represent environmental NPs. However, these proxies do not accurately reflect the physicochemical properties of real-world NPs, as they lack the effects of environmental aging processes such as UV exposure and thermal degradation. To address these limitations, this research investigated the aggregation behavior of NPs released from low-density polyethylene (LDPE) following UV irradiation and heat treatment. We measured changes in physicochemical properties, conducted aggregation experiments in various electrolyte solutions, applied Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, which explains the stability and aggregation behavior of colloidal particles by describing the balance between attractive van der Waals forces and repulsive electrostatic interactions, and developed a mathematical model to simulate aggregation kinetics. Our findings reveal that aging processes, particularly heat treatment, significantly promote NP generation from LDPE and alter their physicochemical properties, including surface charge. NP aggregation is strongly influenced by aging, pH, and cation valence. Heat-aged NPs exhibited enhanced stability due to more negative surface charges, while UV-aged NPs showed complex aggregation behavior in the presence of Ca²⁺, potentially due to bridging effects. In most cases, the observed aggregation behavior can be explained by DLVO theory, and the model developed in this study effectively simulated aggregation kinetics. These results underscore the critical role of aging in NP generation and aggregation dynamics. This study highlights both the applicability and limitations of artificial NP proxies and emphasizes the need for further research on real-world, aged NPs to improve predictions of their environmental fate and transport.