Formation of Secondary Oxidation Products from Nano-plastics in Drinking Water Treatment Processes and Assessment of Their Potential Toxicity

Nano-plastics (NPs) have emerged as a critical concern in drinking water treatment due to their persistence, mobility, and potential to generate toxic transformation products during disinfection. This study provides a comprehensive investigation into the formation of secondary oxidation products from polystyrene Nano-plastics (PS-NPs) during oxidative water treatment processes and evaluates their associated toxicity risks. The research integrates experimental analysis of degradation pathways under ozonation, chlorination, and UV-based advanced oxidation processes (AOPs) with systematic toxicity assessment using luminescent bacteria bioassays. Results demonstrate that ozonation achieves ۹۹.۹% molecular weight degradation and ۴۲.۷% mineralization of PS-NPs within ۲۴۰ minutes, while chlorination exhibits substantially lower efficacy with only ۷.۱% molecular weight degradation. However, the formation of oxygen-containing intermediates including formic acid, phenol, acetophenone, and hydroquinone during ozonation raises concerns regarding secondary contamination. UV/PMS treatment achieved ۶۳.۹% mineralization but resulted in ۹۸.۱۹% inhibition of luminescent bacteria, indicating significant toxicity of degradation intermediates. By contrast, UV/NaClO showed lower toxicity (۲.۹۷% inhibition) but limited mineralization efficiency (۷.۰%). These findings underscore the critical knowledge gap regarding the trade-off between NP degradation efficiency and the formation of toxic secondary products, highlighting the urgent need for integrated treatment strategies that address both NP removal and byproduct toxicity.

کلیدواژه ها:

Nano-plastics ، Secondary oxidation products ، Disinfection by-products ، Advanced oxidation processes ، Toxicity assessment