Effects of UV-based oxidation process on the degradation of ethylene propylene diene monomer based tire-derived microplastics: Fragmentation, leaching, and disinfection byproduct formations

Tire-derived microplastics, especially those composed of ethylene propylene diene monomer (EPDM), pose a growing threat to drinking water systems due to their persistent nature and potential to release toxic additives and disinfection byproduct precursors. Among TMPs, tire wear particles and crumb rubber, particularly green and grey variants used in artificial turfs, contribute significantly to environmental loads. This study investigates the effects of EPDM-based tire chips and crumb rubbers under UV and with the influence of diminishing Hydrogen peroxide (H 2 O 2 ). All samples showed evidence of fragmentation, with tire chips exhibiting the highest weight loss (1.18 %) and increased carbonyl index, indicating oxidative surface breakdown. Organic leaching was confirmed by a peak in total organic carbon (6.2 mg/L), which later declined as the exposure continued. Post-chlorination analysis detected chloroform, a regulated trihalomethane, at 22 µg/L, highlighting DBP formation potential. UV/H₂O₂ accelerated early degradation but lost efficiency over time due to H₂O₂ instability due to the consumption by UV. Zinc leaching from tire chips reached 15 mg/L, exceeding drinking water standards (1 mg/L). In contrast, green crumb rubber showed greater resistance to degradation, likely due to stabilizing additives. These results demonstrate the dual impact of UV-based AOPs in both degrading TMPs and mobilizing hazardous constituents, underscoring the need for optimized treatment strategies. • EPDM-based tire particles undergo fragmentation under UV and UV/H₂O₂ exposure. • Zinc concentrations from tire chips reached > 15 mg/L during oxidation treatments. • Organic carbon and chloroform levels indicate DBP precursor leaching from TMPs. • Stabilizers in green crumb rubber improve resistance to UV-induced degradation. • H₂O₂ boosts initial degradation but degrades quickly, reducing long-term effects.