Polymer-Dependent Microplastic-Derived DOM Modulates Singlet Oxygen Formation and BPA Degradation in the UV/PMS System

Microplastic-derived dissolved organic matter (MPs-DOM) released during photoaging can mediate aquatic photochemistry, yet its influence on reactive-species formation in UV/peroxymonosulfate (UV/PMS) systems remains unclear. Herein, MPs-DOM generated from ultraviolet-aged polystyrene (PS), polyethylene terephthalate (PET), polyethylene (PE), and polycaprolactone (PCL) was characterized to evaluate its effects on bisphenol A (BPA) degradation in the UV/PMS system. PET-DOM exhibited higher aromaticity and a higher degree of oxidation, whereas PS-DOM was characterized by less oxidized aromatic structures. Kinetic experiments showed polymer-dependent effects on BPA degradation: PET-DOM produced the highest apparent rate constant (kobs = 1.1051 min–1), PE-DOM and PCL-DOM showed intermediate enhancement, whereas PS-DOM inhibited BPA degradation (kobs = 0.4391 min–1). Reactive oxygen species (ROS) analyses showed that the estimated residual nonradical contribution exceeded 90% in the MPs-DOM-containing systems, while complementary probe and EPR results supported an important role of 1O2-related oxidation. PET-DOM exhibited higher 3DOM* and 1O2 levels together with enhanced BPA degradation, whereas PS-DOM showed lower BPA degradation despite detectable 1O2 formation. Together, these results establish a link between MPs-DOM composition, excited-state reactivity, electron-transfer behavior, and 1O2-related BPA oxidation under controlled UV/PMS conditions.