Synergistic effects of chlorination and photoaging on tire related particles aging and tetracycline adsorption: Experimental and molecular dynamics insights.

Tire related particles (TRPs) are widely distributed and critically important vectors for coexisting antibiotics in aquatic environments. As a major source entering surface waters, TRPs from wastewater treatment plants undergo disinfection and subsequent photoaging. Accordingly, this study investigates the combined effects of chlorination (a widely used disinfection method) and photoaging on TRPs' physicochemical properties and the adsorption of tetracycline (TC). Experimental observations suggest a possible synergistic ("1 +1 >2") effect where the combined chlorination and photoaging may produce a more pronounced aging effect than either process alone. Adsorption isotherm and adsorption kinetics suggested a tendency for moderate aging enhances adsorption, while excessive aging leads to a decrease in the overall adsorption affinity. Molecular dynamics simulations demonstrated interplay between decreased compactness, increased surface heterogeneity, and hindered site accessibility, explaining the observed transition from enhanced to inhibited TC adsorption with increasing aging. Furthermore, experimental adsorption studies revealed TC adsorption may facilitate the release of some TRPs' additives. Density functional theory calculations supported this observation, indicating that when the interaction energy between the additive and the TRPs is less than that between TC and the TRPs, the additive is preferentially replaced by TC. Collectively, these findings highlight the synergistic effect of chlorination and photoaging and underscore the potential for TRPs additives to be released into the surrounding environment upon interaction with coexisting organic contaminants.