True-to-life microplastics obtained from PP pasta bags for efficient removal of pharmaceutical contaminants in aqueous systems

The accumulation of microplastics (MPLs) in natural environments poses an increasingly serious threat to ecosystems and human health, either as microplastics themselves or as carriers of other contaminants. Moreover, the scarcity of information regarding the properties of real microplastics and their interactions with pollutants is problematic. This study investigates the possibility to use true-to-life polypropylene (PP) microplastics obtained from post-consumer plastic products through processes that mimic natural environmental ageing as tool for contaminants removal in aqueous systems. Specifically, PP pasta bags were left untreated or subjected to 96 h of photo-oxidation, followed by mechanical fragmentation. When photo-oxidized, microplastics were obtained through fragmentation of the films: they present distinct chemical and physical properties compared to the untreated macro-fragments. The samples were characterized in terms of surface chemistry, hydrophilicity, crystallinity, mechanical properties, density and morphology. They were then tested as sorbents for two common pharmaceutical contaminants: paracetamol (PCM) and ciprofloxacin (CFX). Adsorption experiments showed that the photo-oxidized samples had significantly higher adsorption capacities than unaged PP, demonstrating that environmental degradation greatly increases the reactivity of MPLs. The kinetic data were analysed using the PFO, PSO and Elovich models, with the PSO model providing the best fit. This suggests a two-step adsorption mechanism involving initial physical interactions followed by sorption. PCM exhibited a higher affinity for the sorbents, whereas the structural complexity of CFX resulted in slower adsorption kinetics. This study proposes exploiting MPLs positively as an unconventional tool for environmental remediation, with possibility of reuse.